OASTlK'l-ol'A 

 ImbrUU.) 



of it more gentle, and the edge of the umbilicus more narrowly rounded. The 

 veutr.il >i<le of the volutions being flatter, the umbilicus therefore is not only more 

 abrupt at its circumference, but also a little smaller. The transverse imbrications, 

 though not quite so oblique, are similarly disposed, but the serrations are broader 

 aii'l fewer in number, there being on each side only six or seven, to ten or eleven 

 in C. "fili'iH'i. Iii < '. <,,mi>ressa Conrad the transverse imbrications are but little, if 

 at all. oblique, and the dorso- ventral diameter of the whorls the greater, while for 

 C. si mi Us the opposite is true. 



formation ad locality. Ui>\ r parlnf tli.- Hlac-k River group. In Mercwrand Hoylt ..... unties, Kentucky. 

 . E. O. Ulricb. 



CONRADKLLA FIMBRIATA, II. Sp. 

 IM.ATK I. XII. FIO. M: PLATK I.XVII. KIO8. 7-10. 



Shell <li-coi.i. from IS mm. to 25 mm. in diameter. Volutions about three, 

 more rapidly than u-ual for the genus, very strongly and rather abruptly 

 carinate, broadly suhcordate in section, wider than high, narrowly rounded in the 

 lower part of the sides; umbilicus comparatively small, equalling two-fifths of the 

 diameter of the shell; slit extending nearly a half- volution posterior to the apertural 

 margin. Aperture abruptly expanded at frequent intervals, the expansion left 

 behind forming transverse, imbricating, folded lamellae, the anterior edges of which 

 are strongly serrated and project, collar-like, 3 or 4 mm. forward and outward from 

 the surface of the last volution. Each expansion has seven folds, the lower one 

 faint, the upper ones strong. Occasionally a smaller one is developed between each 

 pair of the latter. The entire surface covered by very fine longitudinal and trans- 

 verse lines. All the transverse markings cross the volutions obliquely. When, as 



nerally the case, the projecting lamella? are broken away, the surface presents 

 two or three more or less obscure revolving ribs on each side of the prominent keel. 

 Greatest width of last volution, without the apertural expansion, in a specimen 25 

 mm. in diameter, about 12 mm.; with the expansion about 18 mm.; bight of 

 aperture about 15 mm. Intervals between imbrications varying on the outer 

 whorls between 1 and '2 mm. 



When the apertural expansions are broken away this shell reminds one greatly 

 of C. simili.t, the only difference being that the whorls enlarge more rapidly. Hut 

 the perfect shell cannot be confu-c.l with any other, the great extent of the over- 

 lapping expansions giving it a very striking appearance. 



Formation and locality. Sl>n* Kivrr k'r<>ii|i(\ anux.-im Minnesota, and Dlxnn 



Illinois. 



Oollectiott. Geological and y - XinoesoU (about 22 s i-n I. O. Ulrlrh 



'. -]..:!. M] 



Mu#vm Reguter, Nos. 063, 5110, 8724. 



