12 BULLETIN NO. 2. 



extremity short and rather more narrowly rounded than the pos- 

 terior, and descending obliquely from the beaks. Beaks com- 

 pressed, extending beyond the cardinal border, and located about 

 one-fourth the entire length of the shell behind the anterior 

 extremity. Surface of the cast ornamented with rather strong 

 parallel lines of growth. 



Length 3^% inches ; height from the beak to the basal margin 

 1 J inches ; convexity of the valves about -f^ inch. 



This species resembles A. suhcuneata in size and form, but lacks 

 the concentric undulations of that species. 



Position and locality : Keokuk limestone, Warsaw, 111. 



No. 2540 of tlie Illinois State collection. 



Collector, A. H. Worthen. 



ALLORISMA ELONGATA. (sp. nOV.) 



Shell large, very elongate, dorsal and ventral margins nearly 

 straight and parallel ; length three times as great as the height ; 

 greatest convexity in the umbonal region ; cuneate and perhaps 

 a little gaping behind, with a rather narrowly rounded outline. 

 Beaks recurved, approximate, and located near the anterior ex- 

 tremity. Anterior margin evenly rounded. The surface of the 

 cast shows numerous concentric undulations that are much smaller 

 and more numerous than in A. suhcuneata, its nearest represen- 

 tative form. 



Length 3-]f inches; height 1{\ inches; breadth near the umbo 

 1^ inches. 



Position and locality: Keokuk limestone, Warsaw 111. 



No. 2542 of the Illinois State collection. 



Collector, A. H. Worthen. 



GENUS SOLENOMYA, Lamark. 



SOLENOMYA VARSOVIENSIS. (sp. nOV.) 



Shell rather large, elongate-oval or sub-elliptical in outline, 

 moderately convex, and apparently closed at the extremities. The 

 greatest convexity of the valves is in the umbonal region, and 

 thence obliquely to the ventral margin, and in front of this ele- 

 vated region a slight depression may be seen which extends 

 nearly to the anterior extremity. Beaks depressed and recurved 

 towards the posterior margin, and located a little less than one- 

 third the entire length of the valve behind the anterior extremity. 



Dorsal and ventral margins nearly straight and sub-parallel, 

 anterior extremity rather narrow, and the posterior broadly rounded. 



Surface of the cast marked by a few obscure wrinkles near the 

 umbo, and lines of growth towards the ventral margin. 



Length about 3 inches ; height from the beak to the ventral margin 

 1^ inches; convexity of the valves about ^-^ inch. 



Position and locality : Keokuk limestone, Warsaw, 111. 



No. 2539 of the Illinois State collection. 



Collector, A. H. Worthen. 



