249 



Gems GOSSELETTIA. Barrois. 



[Ety. : Proper name.] 

 (1881: Ann. Soe. Geol. du Nord, Vol. VIII.. p. 170.] 



Shell sub-triangular, truncate on the anterior side, sub-alate 

 on the posterior side. Ligamental area wide, longitudinally 

 striate. Cardinal teeth strong, situated under the beak. 

 Lateral teeth elongate. Surface marked by concentric stria-. 



GOSSELETTIA RETUSA. Hall. (Fig. 104.) (Pal. X. Y.. 

 Vol. V., Pt. I., p. 266, PI. XXXIII.) 



Distinguishing Characters .— Oblique rhomboidal outline; 

 "anterior margin nearly straight for two-thirds of the 

 length, inflated at the byssal opening, and concave below." 



Fig. 164. Oosselettia retusa. Left andantero-cardinal view of the t3'pe specimen, from 

 Eighteen Mile Creek (from Hall). 



Found "in the Hamilton group, at Eighteen Mile Creek, 

 Erie County, X. Y." (Hall, type.) 



Genus MODIOMORPHA. Hall. 



[Ety. : Modiola, a genus ; morplie, form.] 

 (1870 : Preliminaiy Notice Lamellibranehiata, 2. p. 72.) 



Shells with equal but very inequilateral valves, which are 

 sub-ovate in outline, largest posteriorly, and with a rounded, 

 projecting anterior end. A depression, or "cincture," passes 



