"Whether we endeavor to arrange the families and genera of spiders in a continuous series, from that group which is looked upon as the most perfect down to the lowest, or vice-versa, or whether we arrange them according to some other principle, we are soon met by the same difficulties, which present themselves, whenever we endeavor to arrange in such a manner any class or order whatever of the productions of nature. As regards the larger groups of spiders, the suborders and the familles, the reasons for the order of arrangement we have chosen will, we hope, easily be seen if one casts one's eye on the accompanying diagram, which gives a view of the connection founded on real affinity, which the families of the spiders adopted by us, according to our opinion, have to each other."

In a note, the author expresses his belief with Darwin, that "propinquity of descent is the hidden connection which our classifications attempt to find and express.

The work closes with a list of the genera of fossil spiders found in Europe, compared with living genera.-J. H. E.

GEOGRAPHY AND ARCHEOLOGY OF PERU.* - While in England recently, Mr. Squier was induced by his friends to reprint in pamphlet form the paper which he read before the American Geographical Society in February last. We gave an abstract of that portion of the lecture which related to the Archæology of Peru in the NATURALIST for September; but the present pamphlet contains much interesting and important information relating to the geography of the great Titicaca basin to which we did not allude in our former notice, and will well repay reading by all interested in this great centre of a prehistoric nation.

NATURAL HISTORY MISCELLANY.

ZOOLOGY.

MORPHOLOGY AND ANCESTRY OF THE KING CRABS. In a communication to the Boston Society of Natural History, Oct. 17, 1870, Dr. A. S. Packard, Jr. stated that a study of the embryology of Limulus, as well as its anatomy, led him to consider, as several authors had done, from Savigny and Van der Hoeven down to the present time, the anterior division of the body as a cephalothorax, the posterior division being the abdomen. Latreille, Milne-Edwards, and more recently Mr. Henry Woodward, † the distinguished palæontologist, have regarded the anterior division of the body as the head, and the posterior division as embracing the thorax and abdomen, the last three segments in Mr. Woodward's opinion, including the telson, representing the abdomen. Against this view he thought could be brought the embryological facts already stated at the meeting of the American Association for the Advancement of Science at Troy. He there stated that the germ first started as a Nauplius and that just previous to moulting a Nauplius-skin in the egg, the abdomen was differentiated from the cephalothorax. In this latter region (composed of six segments) are contained not only the eyes, simple and compound, but all the ambulatory appendages, which surround the mouth and are true maxillipeds, no antennæ or thoracic appendages being developed. This region contains the stomach and a considerable portion of the intestine, and the liver, which opens into the intestine near the middle of the cephalothorax, sending but a single pair of biliary tubes into the abdomen. The anterior half of the dorsal vessel, with two pairs of arteries and two pairs of valvular openings, is situated in the cephalothorax.

* Observations on the Geography and Archeology of Peru. By E. G. Squier, M.A., F.S.A. etc. 8vo. pamph. London. Trubner & Co., 1870. (Price 25 cents. Address Naturalists, Agency.)

On some Points in the Structure of the Xiphosara. Quarterly Journal of the Geological Society of London for Feb. 1867.

Lastly, the genital openings in both sexes are situated on the first pair of abdominal lamellate appendages, the testes and ovaries lying wholly in the cephalothorax; the ovaries, when distended with eggs, filling up the front of the cephalothoracic shield.

The abdomen consists of nine segments, the long spine-like telson forming the ninth, as seen plainly in the embryo. The abdominal cavity is small, the abdomen being very thin, and mainly filled with the muscles attached to the lamellate feet.

There are, then, in Limulus, no thoracic feet, comparable with those of the Decapods and the Tetradecapods, and the thoracic region (as much of it as exists), is merged with the head, in fact never becoming differentiated from the head proper. Thus we have in Limulus a crustacean with the body divided into two regions; a cephalothorax (the thorax being potential, viewed externally, with no appendages or segments to indicate its existence) and a nine-jointed abdomen.

This disposition of the body-segments is paralleled by the zoëa, or young, of the Decapods. In the freshly hatched zoëa the body is divided into two regions; the cephalothorax, with no trace at first of thoracic segments, or thoracic appendages, (the two pairs of large feet being deciduous maxillipeds), the thorax not being yet differentiated; and a five-to-seven-jointed abdomen. The size of the cephalothorax, as compared with the abdomen, varies greatly in the different forms of zoëæ, some zoëæ strongly resembling Eurypterus in the small cephalothorax. After the first moult five pairs of rudimentary thoracic limbs arise at the hinder portion of the cephalothorax, thus proving our statement that the cephalothorax of Limulus, and consequently the so-called "head" of Eurypterus and Pterygotus, combines a head with a potential thorax, the latter never becoming differentiated in subsequent moults.

In the Trilobites, however, according to the late discovery of Mr. Billings, the thoracic segments bearing jointed feet are developed; though, as shown by Barrande, the larval trilobite is hatched either without any, or with but a single, thoracic segment. Limulus, Eurypterus, Pterygotus, and their allies (Huxley has aptly compared the Eurypteridea to a zoëa), with the Phyllopods, may be considered as virtually zoëæ, or to be more precise, (since they lack many important characters of zoëæ), retarded or retrograde zoëæ.

Speculating on the ancestry of the members of the subclass of Branchiopoda, he would trace them all to a common Nauplius form, as Haeckel, Fritz Müller, and Dohrn had done. This Nauplius form may have existed in the Laurentian Period, as we already find highly organized Trilobites, Phyllopods, and Ostracodes in the lowest Silurian strata. He

*Though in his communication to the American Association he has spoken of the Branchiopoda as an order, of which he regarded the Paciloptera as a suborder, he thought the term subclass preferable, as, with the subclasses Decapoda and Tetradecapoda, etc., they were much more general groups than the orders of Vertebrates as first limited by Linnæus, whose idea of an order we should follow for the sake of uniformity, just as the term family should be applied in the sense in which Latreille used it.

suggested that the modern Phyllopods, such as Apus and Branchipus, may have descended perhaps, by two parallel lines of descent from certain Silurian Copepoda and Ostracoda. He accounted for the origin of these forms rather by a process of acceleration and retardation of development as suggested by Messrs. Cope* and Hyatt,† involving a more or less sudden formation of generic forms, than by the theory of Natural Selection, which involves an indefinite number of slight modifications for the production of even a variety, and such a succession of intermediate generic forms as we do not find recent or fossil. He also thought that the study of the facts of Dimorphism and Parthenogenesis, and the mode of production of the more remarkable sexual differences among animals, would throw light on a comprehensive theory of evolution.

THE ANCESTRY OF INSECTS. Referring to his discovery of Pauropus in this country, and mentioning the six-legged form of the young, and its resemblance to Podura, and comparing it with the Hexapodous young of Julus and the young of certain mites, Dr. Packard, at the same meeting, referred the ancestry of the Myriapods, Arachnids, and Hexapodous Insects to a Leptus-like terrestrial animal, bearing a vague resemblance to the Nauplius form among Crustacea, inasmuch as the body is not differentiated into a head, thorax or abdomen, and there are three pairs of temporary appendages. Like Nauplius, which was first supposed to be an adult Entomostracan, the larval form of Trombidium, had been described as a genus of mites under the name of Leptus (also Ocypete and Astoma) and was supposed to be adult.

For this primitive, ancestral form he proposed the term Leptus. He suggested that the ancient Leptus may have descended through Demodex from some Tardigrades, and that this latter group had perhaps descended through some form like Linguatula, from a true terrestial worm, like the remarkable Peripatus, for example. The Myriapods may, through a parallel line of descent, have been evolved from some Leptiform animal like the young of Pauropus, while the Hexapoda may have descended by a parallel line of descent through some Leptiform Silurian insect resembling the young of Stylops, Meloe, and low neuropterous or orthopterous larvæ, and the Thysanura, such as Podura and Lipura. He did not regard the insects as having been evolved either from a zoëa or Nauplius form, but would refer the ancestry of both classes (the Insects and Crustacea), independently of each other, to the worms (Annulata).

MONTEREY IN THE DRY SEASON. - On returning to the coast from the Colorado valley in May, 1861, my health impaired by the tropical heat of the last two months at Fort Mojave, and by the too sudden change to the foggy climate of the coast, I was glad of the opportunity of recruiting it by some weeks devoted to collecting marine animals, etc., at Monterey. 'Origin of Genera. Philadelphia. 1868.

+ Parallelism between the order and individual in the Tetrabranchiate Cephalopods. Memoirs of the Boston Society of Natural History, 1866, and AMERICAN NATURALIST, Vol. 4, pp. 230 and 419.

Leaving, therefore, my military companions at San Diego, I travelled to San Francisco by land, picking up about forty species of Mollusca at points along the southern coast.

My preparations for dredging, determining my collections, and describing the new vertebrates detained me in San Francisco until August 9th, when I went to Monterey by steamer. There I remained until September 26th, dredging, and collecting along shore chiefly Mollusca, but not neglecting other animals. The additional species collected were thirty-two of Vertebrata, one hundred and seventy-five Mollusca (thirty new species) twenty-seven Radiata and twenty-six Articulata (marine, as I kept no account of the land species constantly preserved). As I have written a very full report of the Mollusca collected, for the American Journal of Conchology, and as most of the other invertebrates have never been determined, because they were lost in the ill-fated steamer "Golden Gate," together with a large collection from the southward, made previous to June, 1862, I can give little that is new or interesting relating to my Monterey collections. The season was the worst for collecting birds, they being in moult; mammals were difficult to obtain and the fishes were chiefly those common in the San Francisco market. Though many whales were killed during my visit, chiefly the "California Gray" (Rachianectes glaucus Cope), it was impossible to obtain measurements and drawings of them as they were always cut up while floating, and the mutilated carcasses when washed ashore were deprived of "flukes" and other essential parts, besides smelling so strong that the odor for miles was almost unbearable.

The land mammalia were chiefly very distinct from those of Fort Mojave, as is naturally to be expected in comparing a well-wooded, fertile region with an almost barren desert. The Grizzly Bear was quite common, though I saw only its tracks. Several others of the large forest quadrupeds, well known as Californian, are doubtless to be obtained by longer and more thorough search than I could make. I got two small rodents, the representatives of species to be found at Fort Mojave, viz: the California Wood-rat (Neotoma fuscipes), and Wood-mouse (Hesperomys Californicus), also one of a genus not found there, the Monterey Field-mouse (Arvicola edax).

The most characteristic land birds were the Vulture (Cathartes Californianus), the Pigmy Nuthatch (Sitta pigmaa), western variety of the Yellow-bellied Fly-catcher (Empidonax flaviventris var. difficilis), Least Titmouse (Psaltriparus minimus). Yellow-billed Magpie (Pica Nuttallii), Western Crow (Corvus caurinus), White-tailed Hawk (Elanus leucurus) besides many representatives of species found in the Colorado valley, such as the Quail (L. Californicus), Bowbill Thrush (H. redivivus), Anna Humming-bird (Althis Anna), Heermann's Song Sparrow (M. Heermanni), Californian and Brown Finches (Pipilo megalonyx and fuscus), while a few seen there only in winter or spring were here breeding, viz: the Black Pewee (Sayornis nigricans) Dwarf Thrush (Turdus nanus), West