52 PROCEEDINGS OF THE ACADEMY OF 



As we have not seen the siphuncle, or the free part of the body chamber of 

 this species it may, possibly, not be a true Lituite. Still, as there is not the 

 slightest appearance of any obliquity of the volutions, as in the genus Trocho- 

 ceras, we have scarcely any doubt in regard to its being a true Lituite. Com- 

 pared with Lituites Marshii, of Hall, (20th Ann. Rep. Regents Univ., N. Y., pi. 

 16, figs. 6 and 7,) from the same horizon, at Kankakee, in this State, our 

 species will be at once seen to differ in having its volutions more compactly 

 coiled together, much less rapidly increasing in size, and ornamented with 

 smaller and much more closely arranged costae. Its costae also make a stronger 

 or deeper backward curve in crossing the periphery, which is rounded instead 

 of being flattened, as in the Marshii. In general appearance it is more like 

 L. (Trocholitcs) ammonius, of Conrad, from the Lower Silurian, though its 

 costre are much more oblique, and differ in being separated by rounded fur- 

 rows quite as wide as the costae themselves ; while its surface shows no traces 

 of the finer sculpturiug seen on that shell. 



Locality and position. Grafton, Illinois ; from a very light drab magnesian 

 limestone of the age of the New York Niagara group. Upper Silurian. 



CRUSTACEA. 



Phillipsia tcbekculata, M. and W. 



Attaining a large size. Head and thorax unknown. Pygidium semielliptic, 

 the length being very nearly four-fifths the breadth, very convex ; posterior 

 margin obtusely rounded ; lateral margins diverging rapidly forward, with 

 convex outlines. Axial lobe well defined, obtuse, and rather promiaeut behind, 

 and gradually widening forward, with nearly straight sides ; rather distinctly 

 more elevated than the lateral lobes, which it nearly equals in breadth at the 

 anterior end, as seen in a direct view from above, but one-fourth narrower 

 than the latter, measuring over the curve of each ; showing sixteen or seven- 

 teen straight, well defined segment, each of which is provided with six small 

 tubercles, arranged so as to form six rows. Lateral lobes with about fourteen 

 segments each, the very short posterior ones being nearly on a line with the 

 axial lobe, while the others grow gradually more transverse anteriorly, so 

 as to show only a moderate obliquity toward the front ; all extending down 

 so as to leave only a very narrow, undefined, smooth marginal space, and 

 each ornamented by from two or three to about twelve tubercles, the number 

 increasing regularly with the length of the segments toward the anterior. 

 Surface oetween the segments and tubercles smooth. 



Length of pygidium, 0-95 inch ; breadth, 1 45 inches; convexity, 0-40 inch. 



This fine species resembles P. ornatus, Portlock, perhaps more nearly than 

 any other, but it attains a larger size, and its pygidium is more broadly rounded 

 behind, with its mesial lobe less rapidly tapering posteriorly; while the rows 

 of tubercles on the segments of its lateral lobes are distinctly more numerous. 

 In general outline, its pygidium more nearly resembles a form figured by 

 Prof, de Koninck, under the name Phillipsia gemmulifera, Phillips, (Aniniaux 

 Foss., pi. liii, fig. 4), though its axial lobe is distinctly narrower, while its 

 lateral lobes are merely provided with tubercles, along the segments, instead 

 of short spines. 



Locality and position. Kinderhook, Pike County, 111. Burlington division 

 of the Lower Carboniferous. 



Phillipsia (Griffithides) bufo, M. and W. 



Entire outline elliptical, the breadth being to the length as 75 to 130. Ce- 

 phalic shield forming more than a semi-circle, round in front and nearly 

 straight behind ; posterior lateral angles terminating in short, abruptly pointed 

 spines extending back to the anterior edge of the third thoracic segment. 



[April, 



