280 UNIONID^. 



curved ; umbones prominent, rugose ; anterior 

 teeth thick, high, triangular, strong ; left hinder 

 strong, (t. 2. f. 13.) 



Young shell with irregular, concentric, nodulose 

 ridges round the umbones. (Pfeffir, ii. t. 2. f. 25.) 



Unio tumidus. Retzius, Nov. Gen. 17. n. 3. ; Forbes and 

 Hanley, B. M. ii. 140. t.40. f. 1. U. rostrata. Studer, Verz. 

 23. Unio tumida. Pfeiffer, ii. 34. t. 7. f. 2, 3., and t. 8. 

 f. 1, 2.; Rossm. Icon. i. 117. t. 3. f. 70. a. b., ii. 27., and 

 t. 14. f. 202, 203, 204. Mya ovalis. Pulteney, Dorset. 27. 

 Unio ovalis. Leach, Syn. Moil. 344.; Flem. B. A. 416. 

 My sea solida. Turton, Bivalves, 246. t. 16. f. 2., Man. 

 ed. 1. 22. f. 13. Mya ovafa. Donovan, iv. t. 122. Unio 

 inflata. Hec. Moll. Valenc.i. 148. U. Michaudiana. Des 

 Moul. Act. Soc. Bourd. vi. 20. U. arcuata. Bouch. Moll. 

 Pays de Cal. 91. 



Inhab. slow rivers. New River, near London, 

 West India Docks, &c. 



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 spe- 

 cimens with pale salmon-coloured pearly insides, 

 which were found in a pond in Warwickshire. 



According to M. Moquin Tandon, this animal in 

 July and August emits small elongated pointed 

 masses consisting of about 100 eggs in each mass. 

 A single Unio will deposit 50 of these masses in two 

 or three days. Moll. France, ii. 578. 



The Abbe Dupuy divides what he considers the 

 French species of Unio into three sections, thus : 



a. Ponderosi. Shell very thick, heavy ; cardinal 

 and laminar teeth very thick; muscular scars 

 deep. 



