50 PROCEEDINGS OF THE ACADEMY OF 



Nautilus (Temnochilus) Winslowi, M. and W. 



Shell attaining a moderatel) r large size, subdiscoidal ; periphery broad and 

 nearly flat, the middle third being rather distinctly flattened, while on each 

 side of this there is a very slight slope outward to the lateral margins. Um- 

 bilicus broad, moderately deep, and showing nearly the full breadth of each 

 inner volution on each side. Volutions apparently about four and a half, 

 with transverse diametar nearly one-third greater than the dorso-ventral ; 

 each ornamented around the lateral margins of the broad periphery by about 

 sixteen very prominent, rounded nodes, which project obliquely outward, at 

 an angle about intermediate between the general plane of the shell and that 

 of the broad periphery, those on opposite sides being alternately arranged ; 

 from these rows of nodes the sides slope abruptly inward, with a moderate 

 convexity, to their inner margins within the umbilicus. Surface marked by 

 rather well defined lines of growth, which curve gently backward in crossing 

 the sides of the whorls from the inner margin, and make a stronger backward 

 curve in crossing the periphery, so as to indicate the presence of a deep 

 rounded sinus in the outer margin of the lip. (Siphuncle and septa unknown.) 



Greatest breadth of a specimen with a part of the outer volution broken 

 away, 4-60 inches ; transverse diameter of outer turn, measuring across the 

 periphery without including the nodes, 2-46 inches ; do. including the nodes, 

 2-93 inches ; dorso-ventral diameter of the outer volution, 1-66 inches. 



This species i3 evidently closely allied to the last, in form and general ap- 

 pearance, but differs in having its volutions proportionally narrower, measur- 

 ing at right angles to the plane of the shell. Its most marked difference, 

 however, consists in the form of its nodes, which are round, instead of being 

 distinctly compressed. It seems to be also related to If. tuberculatus of Sow- 

 erby, but differs from the published figures of that species in having its peri- 

 phery proportionally broader, and distinctly more flattened ; while its nodes 

 are placed nearer the outer margin of the whorls, as well as more prominent. 

 From N. Occidentalis, Swallow, (= N. quadrangularis, McChesney), it will be 

 readily distinguished by the greater transverse diameter of its whorls, which 

 are also without the flattened sides of that species, and differ in wanting the 

 two mesial rows of nodes on the periphery. 



This specific name of this fine Nautilus is given in honor of Dr. J. C. Wins- 

 low, of Danville, Illinois, to whom we are indebted for the use of the specimen 

 from which the description was drawn up. 



Locality and position. Danville, Illinois, from the shale over the fifth bed of 

 coal, of the corrected Illinois section ; being near the horizon of the upper 

 part of the Lower Coal-Measures. 



Nautilus (Temnochilus) Coxanus, M. and W. 



Shell rather small, subdiscoidal, broadly rounded, or depressed convex 

 over the periphery; umbilicus wide, rather deep, perforated, and showing 

 more than three-fourths of the dorso-ventral diameter of each inner turn. 

 Volutions about two and a half to three, increasing gradually in size, wider 

 transversely than dorso-ventrally, very slightly concave along the dorsal or 

 inner side for the reception of the periphery of each succeeding turn within, 

 more or less narrowly rounded (subangular in some small specimens) and 

 ornamented by about fifteen small nodes around the middle of each side, 

 from which point the inner side rounds very abruptly into the umbilicus. 

 Septa separated, on the outer or ventral side, by space about one-fifth or one- 

 sixth the transverse diameter of the volutions at the point of measurement ; 

 arching very slightly backward in crossing the periphery. Body chamber 

 composing about half of the outer volution. Siphuncle small, and situated 

 subcentrally, or somewhat nearer the outer side. Surface ornamented with 

 distinct, regular, longitudinal, raised lines, or small costa j , narrower than the 



[April, 



