. Annual report of the regents of the university of the state of New York on the condition of the State Cabinet of Natural History and the historical and antiquarian collection annexed thereto. Science. 378 TWENTIETH REPORT ON THE STATE CABINET. Formation and locality. In limestone of the Niagara group, at Wauwa- tosa; and a single specimen of doubtful locality, received from Mr. I. A. Lapham, has the aspect of the Bridgeport rock. ILL^NUS IOXUS (). PLATE 22 (13), FIGS. 4-10. Illcenus barriensis, page 332 (28). " " Pal. N. Y., Vol. ii, pa. 302, pi. 66. Probably not identical with
. Annual report of the regents of the university of the state of New York on the condition of the State Cabinet of Natural History and the historical and antiquarian collection annexed thereto. Science. 378 TWENTIETH REPORT ON THE STATE CABINET. Formation and locality. In limestone of the Niagara group, at Wauwa- tosa; and a single specimen of doubtful locality, received from Mr. I. A. Lapham, has the aspect of the Bridgeport rock. ILL^NUS IOXUS (). PLATE 22 (13), FIGS. 4-10. Illcenus barriensis, page 332 (28). " " Pal. N. Y., Vol. ii, pa. 302, pi. 66. Probably not identical with I. barriensis of Murchison, Silurian System. There are several slight differences between the American (Wisconsin) specimens referred to this species, and the figures and descrip ? of the English form of I. barriensis, as given in the British Decade 2, pi. 3 and 4. None of these differences, however, appear to be very important or strongly marked. On the head the eye is placed a little more obliquely; the mova- ble cheek is comparatively longer from the posterior angle to its anterior margin; the facial suture lines unite with the rostral suture, forming an abrupt angle instead of a rounded one ; the rostral shield is proportionally narrower from side to side, especially on the inner margin, where it unites with the hypostoma. The differences in the pygidium are not readily observed. We have no means of comparing the articulations of the throax in the Wisconsin specimens. The New-York specimens usually referred to I. barriensis have the same form of head and pygidium as those of Wisconsin, and differ from the figures of the British species in the direction of the terminations of the pleura. Notwithstanding the differences are not conspicuous, I am inclined to regard them as of the same importance as those which distinguish closely allied species. The accompanying outline figure shows the direction of suture lines and form of rostral shield in this species of Please
Size: 1977px × 1264px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1850, booksubjectscience, bookyear1853
