298 CONCHIFERA. 



Mya ovalis. Montag. T. B. 563. ; Donov. B. S. t. 



89. 

 Mya ovata. Wood, Conch. 105. t. 19. f. 5. 



depressa. Don. B. S. iii. t. 101. 



Mysca ovata. Turt. Biv. 246., Man. ed. 1. 21. 



f. 12. 

 Unio Batava. Lam. Hist. vi. 78. ; Pfeiffer, i. t. 5. 



f. 14. 

 Young shell elliptical-ovate. Pfeiffer, ii. t. 2. f. 23. 



Inhab. slow rivers. 



This shell, of which I have not seen a specimen, ap- 

 pears to differ in being shorter and higher than Unio 

 tumidus. If it is the same as Pfeiffer's, it retains the 

 same character in its very young state. But Dr. 

 Turton's figure is probably copied from Wood's ; and 

 I am not certain that his figure was not taken from a 

 slightly distorted U. tumidus with an irregular hinge. 

 It is a very doubtful British species. 



Mr. James D. C. Sowerby has sent me a speci- 

 men which he considered at the time that he made 

 the figures for the first edition, to be like Dr. Tur- 

 ton's species ; it is only a distorted specimen of U. 

 tumidus, with the lunule much and irregularly en- 

 larged, and the anterior teeth much distorted. Mr. 

 Alder considers U. tumidus (Mysca solida and M. 

 ovata Turt.), U. pictorum, U. rostrata Lam, and 

 U. Batavus Lam., as distinct British species. (Mag. 

 Zool. Sf Bot. ii. 118.) I have never been able to 

 distinguish more than two, U. pictorum and U. tu- 

 midus. 



