Lepidolires, Cerionitcs.l 



SPONGES, GRAPTOLITES, CORALS. 67 



LEPIDOLITES, Ulrich.* 



PLATE F, FIGS. 11, 12. 



1879. Lepidolites, ULRICH. Jour. Cincinnati Soc. Nat. Hist., vol. ii, p. 20. 

 1885. Ischadites, JAMES. Ibidem, vol. viii, p. 163. 

 1891. Beceptaculites, JAMES. Ibidem, vol. xiv, p. 60. 



Lepidolites is closely related to Ischadites, but possesses a few features that will not 

 allow it at present to be regarded as synonymous with the latter. The spicular 

 head-plates in Ischadites Dr. Hinde (op. cit. p. 812) describes as follows : "As a rule 

 the margins of the plates appear to fit closely and evenly to each other so as not to 

 leave any interspace between their edges, but in some cases the upper or front mar- 

 gins seem to be slightly elevated as if they imbricated over the lower or hind margins 

 of the spicular plates immediately in front, and left a small intermediate space, now 

 filled with the matrix." The head-plates in Lepidolites are very thin, strongly 

 imbricating and wavy along their edges. While these sponges are more or less 

 distorted, this overlapping character of the plates cannot be ascribed to pressure. 

 Again, in Ischadites the head-plates increase in diameter from the nucleus to the 

 zonal region, and then decrease in size towards the summit, but in Lepidolites, they 

 gradually become larger from the center of the base to the upper portion of the 

 sponge. The vertical or fifth ray of the spicules in Lepidolites is very short and 

 terminates bluntly, while in Ischadites it is long and slender, gradually tapering and 

 terminating in a point. This ray (the fifth) does not project free into the cavity, but 

 lies flat and directed downward, with neighboring ones side by side, so that the 

 result of the arrangement is an imbrication comparable with narrow shingles. 



L. DICKHATJTI Ulrich. 



1879. Lepidolites aiekhauti ULRICH. Jour. Cincinnati Soc. Nat. Hist., vol. ii, p. 21, pi. 7, flgs. 17-17b. 



1879. Lepidolites dongatus ULRICH. Ibidem, p. 22, pi. 7, flg. 16. 



1885. Ischadites dickhauti JAMES. Jour. Cincinnati Soc. Nat. Hist., vol. viii, p. 165. 



1891. Keceptaculites dickhauti JAMES. Ibidem, vol. xiv, p. 63. 



Mr. Ulrich agrees that the name L. elongatus is superfluous. 



Formation and locality. Cincinnati group ; Oovington, Kentucky. 



CERIONITES, Meek and Worthen. 



1868. Cerionites, MEEK and WORTHEN. Geological Survey of Illinois, vol. iii, p. 346. 



Type Lunulites? dactylioides OWEN. 



C. DACTYLIOIDES Owen, Sp. 



1844. Lunulites ? dactioloides OWEN . Geological Report Iowa, Wisconsin and Illinois, p. 69, pi. 13, flg. 4. 

 1868. Cerionites (Pasceolus?) dactylioides MEEK and WORTHEN. Geological Survey of Illinois, vol. iii, 



p. 346, pi. 5, flg. 2. 

 1884. Cerionites dactyloides WHITFIELD. Geology of Wisconsin, vol. iv, p. 267, pi. 13, flgs. 1-3. 



Formation and locality. Niagara limestone; Carroll county, Illinois, and Waukesha. Wisconsin. 

 * We are indebted to Mr. Ulrich for the opportunity of studying his type material. 



