BULLETIN NO. 2. 13 



SOLENOMYA MONROENSIS. (sp. nOV.) 



Shell below the medium size, oblong, the length being a little 

 more than twice the height from the beak to the ventral margin ; 

 valves moderately convex, the greatest convexity being obliquely 

 along the umbonal slopes from the beaks to the ventral margin • 

 cardinal margin straight and about three-fifths the entire length of 

 the valve ; basal margin slightly sinuous, from a shallow denression 

 that extends obliquely from the beaks to the opposite margins 

 extremities rounded ; beaks depressed, oblique, and located about 

 one-sixth the entire length of the valves behind the anterior 

 extremity. 



Surface smooth or showing only a few obscure lines of growth. 



Length of the largest specimen obtained f| inch; heisht froni 

 beak to base j\ inch. 



Position and locahty : Obtained from the oolitic beds of the St. 

 Louis limestone on Fountain creek, Monroe county, 111. 



No. 25 J 5 of the Illinois State collection. 



Collector, A. H. Worthen. 



SOLENOMYA? lOWAENSIS. (sp. nOV.) 



Shell small, narrow, oblong, valves apparently closed at each 

 extremity. 



Dorsal and ventral margins nearly parallel, beaks depressed 

 and situated close to the anterior extremity. Surface markings 

 unknown. 



Length of the largest specimen seen f^ inch ; height } inch • 

 thickness ^ inch. This little shell is only known from a few 

 casts obtained from the shaly layers of the St. Louis limestone 

 near Pella, Iowa, where it was associated with Allorisma Marion- 

 ensis, Rhijnchonella Ottumwa, Splrlfer Littoni and Zaphrentis sp? 



No. 251/ of the Illinois State collection. 



Collector, A. H. Worthen. 



GENUS AVICULOPINNA, Meek. 



AVICULOPINNA ILLINOIENSE. (sp. nOV.) 



Shell rather larger than the typical species, valves moderately 

 and about equally convex, cardinal and ventral margins curved 

 and converging gradually from the base to the apex. Surface 

 ornamented with numerous thread-like lines or lamella that curve 

 gracefully round to the dorsal margin, and are separated by 

 rather broad spaces on the dorsal portion of the valve. The apex 

 is broken away so that its form cannot be determined. 



Length l^V inches ; greatest width ^ inch ; greatest thickness 

 h inch. This species differs from the A. Americana, in the curva- 

 ture of its margins and the greater convexity of the valves. 



Position and locality: Coal Measures, Peoria county 111 



No. 2529 of the Illinois State collection. 



Collector, Mr. Gifford. 



