Maryland Geological Survey 131 



SuperfamilyCRANIACEA 

 Family CRANIIDAE 



Genus CRANIELLA Oehlert 



Craniella hamiltoniae Hall 

 Plate IX, Figs. 1-7 



Crania hamiltoniae Hall, 1860, Thirteenth Rep. N. Y. State Cah. Nat. Hist., 



p. 77, figs. 4, 5 on p. 76. 

 Crania hamiltoniae Hall, 1867, Pal. N. Y., vol. iv, p. 27, pi. iii, figs. 17-23. 

 Craniella hamiltoniae Hall and Clarke, 1892, Pal. N. Y., vol. viii, pt. 1, pp. 148, 



153, pi. iv I, flgs. 3-lG. 

 Craniella hamiltoniae Schuchert, 1897, Bull. U. S. Geol. Surv., No. 87, p. 193. 

 Craniella hamiltoniae Clarke, 1903, N. Y. State Mus., Bull. 65, p. 219. 

 Craniella hamiltoniae Grabau and Shimer, 1907, N. Am. Index Fossils, vol. 



ii, p. 208, fig. 244. 



Description.- — Shell broadly oval or subcircular. Dorsal valve sub- 

 conical ; apex subcentral or eccentric, pointed in well preserved specimens, 

 often worn or decorticated; exterior surface marked by concentric lamel- 

 lose striae. Ventral or lower valve marked by four strong impressions 

 of the adductor muscle?, which are variable in form ; vascular impressions 

 strongly digitate. 



Three imperfectly preserved specimens of the dorsal or upper valve were 

 found in the bluish shales on the bank of Evitts Creek below Wolfe Mill ; 

 which locality, of those yet studied in Marv'land, has furnished the 

 largest number of specimens of the Inarticulate Brachiopoda. The shell 

 is partly preserved in these specimens and it is shown to be highly punc- 

 tate. The other characters are imperfectly shown ; but the usual muscular 

 scars and apparently the j^eciiliar sigmoid vascular sinus of the upper or 

 dorsal valve are present. It is to be remembered that Hall identified 

 this species from " the Hamilton group in Maryland and Virginia " (Pal. 

 X. Y., vol. iv, p. 28). The specimens were submitted to Prof. Charles 

 Schuchert who agreed in this identification and called attention to the 

 " sigmoid vascular sinus, the generic character of Craniella." 



Length, about 18 mm.; width, 19 mm. 



