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THE INSECT-BEARING SHALES OF COLORADO.
By J. A. ALLEN.
The species described in the present paper is based on some beautifully preserved remains from the insect-bearing shales of Florissant, Colorado. They consist of the greater part of a skeleton, embracing all of the bones of the anterior and posterior extremities (excepting the femora). Unfortunately, the bill and the anterior portion of the head are wanting, but the outlines of the remainder of the head and of the neck are distinctly traceable. The bones are all in situ, and indicate beyond question a high ornithic type, probably referable to the Oscine division of the Passeres. The specimen bears also remarkably distinct impressions of the wings and tail, indicating not only the general form of these parts, but even the shafts and barbs cf the feathers.
In size and in general proportions, the present species differs little from the Scarlet Tanager (Pyranga rubra) or the Cedar.bird (Ampelis cedrorum). The bones of the wings, as well as the wings themselves, indicate a similar alar development, but the tarsi and feet are rather smaller and weaker; and hence in this point the agreement is better with the short-legged Pewees (genus Contopus). These features india cate arboreal babits and well-developed powers of flight. The absence of the bill renders it impossible to assign the species to any particular family, but the fossil ou the whole gives the impression of Fringilline affinities.
PALÆOSPIZA BELLA, gen. et sp. nov. Wings rather long, pointed; tail (apparently*) about two-tbirds the length of the wing, rounded or graduated, the outer featbers (as preserved) being much shorter than the inner. One side shows distinctly six rectrices. Tarsus short, its length a little less than that of the mid. dle toe. Lateral toes sabequal, scarcely shorter than the middle one. Hind toe about two-thirds as long as the middle toe. Feet and toes strictly those of a percbing bird, and the proportionate length of the bones of the fore and hind limbs is the same as in ordinary arboreal Passeres, especially as represented by the Tanagridæ.
* The character of the tail must be given with reservation, since it is not quite certain that the whole of the tail, or that the exact form of the terminal portion, is shown, especially as the preserved impression is somewbat unsymmetrical.
0.80 Forearm, length..
0.95 Manus, length......
1.02 Coracoid, length Clavicle, length...
0.63 Tibia, length.. Tarsus, length. Middle toe and claw. Claw alone.. Hind toe aod claw... Claw alone.
0.15 Wing ..........
3.60 Tail (approximate)...
2.70 Total length (approximate)....
The bones still rest in the original matrix, and, being somewhat crushed and flattened, do not admit of detailed description and com. parison with other types. The furculum is well preserved, and the limb-bones are all in place in their natural relation. The sternum is unrecognizable. The position of the cervical series of vertebræ and the general outline of the skull can be traced; but no structural characters of the bead can bo distinguished, except the proximal portion of the mandible. The long bones all present a well-marked longitudinal groove, due evidently to compression and fracture. This groove is distinctly traceable, even in such slender bones as tibiæ, tarsi, and clavicles. In point of size, while the furculum and the bones of the wing hare all about the same length as the corresponding parts in Ampelis cedrorum, they apparently are considerably stouter. Their greater breadth may, however, be due simply to fattening from pressure. The tibiæ and tarsi are a little shorter than in the species last named, but the difference is only slight.
The most remarkable feature of the specijnen is the definiteness of the feather impressions. Both the shafts and the barbs are shown with great distinctness in the rectrices, and the tips of the primaries of one wing are also sharply defined, overlying the edge of the partly expanded tail. The tip of the opposite wing can also be seen beneath the tail. The feet are so beautifully preserved that even the claws are perfectly distinct. (Plate 1, fig. 1.)
Another specimen from the same locality, and probably representing the same species, consists of the tip of the tail and about the apical third of a half-expanded wing. (See Plate I, fig. 2.) In this example the tail is also pointed and graduated. About seven of the outer primaries of the wing are shown with great distinctness, and two others can be easily made out. The third primary is the longest; the second is slightly shorter; the first and fourth are about equal. There are also in the collection three detached contour feathers of small size, but whether pertaining to the same species as the other specimens cannot, of course, be determined.