MARYLAND GEOLOGICAL SURVEY 121 



CyTHERE ( ?) SHATTUCKI n. sp. 

 Plate XXXYIII, Fig. 10. 



Description. — Valves rather strongly convex in the ventral portion, siib- 

 trapezoidal in outline, the dorsal angles very obtuse, the anterior nuir- 

 gin obliquely rounded and somewhat truncate, the posterior end smaller, 

 drawn out below so that the extremity is very sharply rounded and the 

 outline from that point to the postdorsal angle only very slight con- 

 vex; dorsal margin short, nearly straight, ventral edge long and straight 

 excepting a slight protrusion just behind the mid-length; anterior end 

 with a narrow flattened border; no spines of any sort. Surface some- 

 what tumid in the median ventral region, slightly depressed centrally and 

 posteriorly, sloping more gradually toward the anterior and dorsal mar- 

 gins. Ornament consisting of small, widely separated pits. 



Length of a left valve 0.63 mm., greatest height of same 0.32 mm., 

 greatest thickness of same 0.17 mm. 



This species resembles several of the species referred to Cytlierideis 

 in this work, and when the hinge, which is not clearly shown in the speci- 

 mens so far obtained, is better known it may become necessary to remove 

 it to that or one of the other genera of the family — perhaps Cytherop- 

 teron. Comparing C. shattuchi with our Cytlierideis ashermani and 

 C. longula it may be distinguished at once by its ventral swelling. From 

 the former it differs further in its more acuminate posterior extremity, 

 and from the latter by its shorter form. The surface punctas, finally, 

 are smaller and more distant than in either of the species that, so far as 

 we know, resemble it most, 



Named for Dr, George Burbank Shattuck, of the Maryland Geological 

 Survey, 



Occurrence. — Choptank Formation. Pawpaw Point. 



Collection. — U. S. National Museum. 



Genus CYTHEREIS Jones. 

 Cythere cornuta (Roemer). 



Oytherina cornuta Roemer, 1838, Neues Jahrb. f. Minerl., p. 518, pi. vi, fig. 31; — 



Reuss, 1845, Verstein. bobm. Kreideform., I, p. 10.5, pi. 24, fig. 20. 

 Cythere cornuta Bosquet, 1850, Desc. d. Entomost. Foss. d. Terr. Tert. de laiFr. et 



Belg., p. 117, pi. vi, figs. 4a, b, c, d, Reuss, 1855; Egger, 1858; Speyer, 1863; 



Lienenklaus, 1894. 

 Cythereis cornuta Jones, 1856, Monog. Tert. Entomost, Paleontogr. Soc., p. 39, pi. 



iv, fig. 19, and pi. v, figs. 15a, 15b. 



