148 



Sfreptorhynclins (f) Hallie. 



Locality and Pos'd'wn. — I found the specimens about a mile below 

 Eichmoncl, Indiana, at an old quarry, near the toi^ of the hill, in a field 

 on the east side of the creek. JNot observed elsewhere, so far as known. 



StreptorhyncJms (f) Hallie.— (8. A. JMillee.) 



Fig. 14. Slrf2>lorliiiiicha!<(?) 

 Hallie. Dorsal valve. 



Fi'. 15. Interior of dorsal valve. 



Fig. 16. Interior of 

 ventral valve. 



Shell sub-trigonal in outline, concavo-convex, deflected laterally, 

 resupinate, rather thin and frail ; hinge scarcely equaling the greatest 

 breadth of the valves ; length and breadth about f of an inch. 



Dorsal valve convex in the central part, flattened on the umbone 

 and deflected laterally ; surface marked by moderately coarse, radiating 

 striiie, which increase by intercalation of smaller ones ; area linear, 

 beak not distinct from the edge of the area. Interior, showing cardinal 

 process to be very small and divided into two teeth-like parts, directed 

 a little forward and flattened on their faces ; socket ridges small, short, 

 and oblique ; mesial I'idge scarcely perceptible, without a magnifier, 

 radiating striise plainly visible. 



Ventral valve moderately concave in the central and anterior 

 regions, but slightly convex at the beak, which is perforated and pro- 

 jects slightly beyond the edge of the area ; surface marked by radiating 

 striae, which increase by even bifurcations ; area narrow and sloping 

 laterally ; foramen closed by a rounded deltidium for the reception of 

 the cardinal teeth of the dorsal valve. Interior showing trigonal hinge 

 and circular cavity ; marked by radiating striae. 



This species belongs to the same genus that the shells commonly 

 known as Strojihomena fiUtexta, S. subtcnta, S. planumhona, S. plcinocon- 

 vexo, etc., belong to. They are not, however, included in the genus 

 tStrophomena, and Prof. Hall has suggested that they might be placed 

 in the genus StreTptorhjnclms, while Prof. INIeek "would leave them 

 in the genus Hemipronites. The probability is that a new genus should 

 he, formed to include them and a few other species. 



The specific name is given as a compliment to Miss Hallie Cotton, 

 ■who was the first lady to join the Cincinnati Society of I^atural His- 



