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342

NUMBER CXIII.

XLIV. On the Variability of the Species in the case of certain

Fishes. By Dr. V. FATIO

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PLATEI.

* II.

PLATES IN VOL. XIX.

III.Structure of Stauronema.

IV.

V.

'VI. { VII.)

New Genera and Species of Araneidea.

'VIII. Structure of Hydractinia, Parkeria, and Stromatopora.

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XII. New Hydroida.

XIII. Bdelloidina aggregata-New species of Carpenteria. 'XIV. New Sponges.

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XIX. New Genus and Species of Paleozoic Fossils.
XX. Rupertia stabilis.

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I.-On Stauronema, a new Genus of Fossil Hexactinellid Sponges, with a Description of its two Species, S. Carteri and S. lobata. By W. J. SOLLAS, B.A., F.G.S., &c.

[Plates I.-V.]

OSCAR SCHMIDT's remark, "Die Behandlung der fossilen Schwämme durch die Geognosten und Paläontologen ist eine grausliche," has the merit of being strictly true, though in fairness it ought to be added that the geologists and palæontologists are not wholly to blame for this treatment, since most of their work was done before Schmidt's books had been written, before the Hexactinellidæ and Lithistida (which would have thrown light on their labours) had been discovered, and at a time, one may add, when the sponges in general were the outcasts of the animal kingdom.

To understand aright the fossil sponges, one must obtain a thorough knowledge first of the minute structure of these bodies themselves, and next of the structure and classification of existing forms. The older observers were without the means of acquiring either of these essentials; they consequently, in their attempts at a classification of fossil sponges, were compelled to fall back upon external characters alone, with the addition of what internal features might chance to be revealed by a happy fracture; and since, as we now know, different genera of sponges may assume the same form, and diverse forms may belong to the same genus or even to the Ann. & Mag. N. Hist. Ser. 4. Vol. xix.

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same species, it is easy to see how "dreadful" (grausliche) the treatment must inevitably be which proceeds upon such a basis.

At the present day, however, things are far otherwise with the palaeontologists; the microscope and the lapidary's lathe will give us most of the details we require to know concerning the structure of the fossil forms; and as regards the recent ones, we are here still better off since the researches of Carter and O. Schmidt have given us a scientific knowledge of the organization of a vast number of species, and a good working classification of these into orders, families, and genera. The key to the fossil sponges has thus been placed in the hands of the palæontologist; and if he does not henceforth make good use of it, he will fully deserve the censure which Schmidt has passed so severely upon his predecessors.

In consequence of the assistance and advice which I have received from my friend Mr. Carter, I have been encouraged for some time past to work out the alliances of some of the commoner fossil sponges; and, as a result, I am now able to state that Siphonia pyriformis and costata possess the structure of a Lithistid sponge, and are closely related to the existing species Discodermia polydiscus (Bocage) (Dactylocalyx, Bowerbank), that Stromatopora concentrica and some other species of this genus show no affinities to the Foraminifera, but are Vitreohexactinellid sponges closely resembling Dactylocalyx pumiceus (Stutchbury), and that Manon macropora and a sponge called Chenendopora in the Cambridge Museum belong to the Holorhaphidota (Carter), or sponges whose skeleton consists of acerate spicula closely bound together into a fibrous network. These results, which have been fully confirmed by Mr. Carter, I hope to publish in full in the course of a few months; while in this paper I shall confine myself to an account of a new genus of the Vitreohexactinellidæ occurring in the fossil state in the Gault of Folkestone.

In examining a collection of various fossils brought by Mr. Jukes-Browne from Folkestone, to illustrate his paper on the Cambridge Upper Greensand, I was much struck with some curious forms, which were said to be Ventriculitæ split into halves down the middle; the regularity of the edges, however (which in such a case should have been broken ones), seemed to preclude such an idea, and rather suggested that the forms in question were in a complete state. I wrote therefore to the Folkestone collector, Mr. John Griffiths, re

Except with regard to S. concentrica; Mr. Carter has shown that some Stromatopora are allied to Hydractinia.

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