UNIONID.E. 297 



* * Anterior teeth conical, high. 



1 26. 3. UNIO tumidus. Tumid Union, (t. 2. f. 13.) 

 Shell ovate-elongate, wedge-shaped, tumid, pro- 

 duced and attenuated behind, thick, brown; lower 

 edge curved ; umbones prominent, rugose ; an- 

 terior teeth thick, high, triangular, strong; left 

 hinder strong. 

 Unio tumidus. Retzius, Nov. Gen. 17. n. 3. 



tumida. Pfeiffer, ii. 34. t. 7. f. 2, 3., & t. 8. 



f. 1, 2. ; Eossm. Icon. i. 117. t. 3. f. 70. a. b., ii. 

 27. & t. 14. f. 202, 203, 204. 

 Mysca solida. Turton, Bivalves, 246. t. 16. f. 2., 



Man. ed. 1. 22. f. 13. 

 Mya ovata. Donovan, iv. t. 122. 

 Young shell with irregular, concentric, nodulose 

 ridges round the umbones. Pfeiffer, ii. t. 2. f. 

 25. 



Inhab. slow rivers. New River, near London, 

 West India docks. 



Known from Unio pictorum by being much more 

 solid, having larger and stronger anterior teeth, and 

 by its tapering behind. 



Mrs. Corrie has very kindly sent me some speci- 

 mens with pale salmon-coloured pearly insides, which 

 were found in a pond in Warwickshire. 



127. 4. Umoovalis. Oval Union, (t.2. f. 12. ?) Shell 

 elliptical-ovate, thick, yellowish green rayed, 

 tapering behind ; hinder margin slightly arched, 

 or contracted ; umbones prominent, wrinkled, 

 often worn ; cardinal teeth thick, conical, cre- 

 nated. 



o 5 



