TRIBE NAYADES. 195 
teeth lamelliform and double in the right valve only, the lateral 
straight. 4..13.—R. Hoogly, Hindostan. 
U. Oxivarius. Lea. on U. 1. p.118. (and Tr. Am. Ph. 4.) 
t. 16. f. 38.—Benson. Ovate-oblong, transverse, inequilateral, 
very thin, pellucid, smooth, anteriorly subattenuated, ventral edge 
somewhat rounded; beaks slightly elevated, rounded, not undulated ; 
ligament very small, cuticle olive, very smooth, rays obscure, nacre 
white and pearly : cardinal teeth large erect and lamelliform, lateral 
short and lamelliform. +4..13.—Jndia. 
U. Batavus. Lam. 33.—Schret. Fluss. t. 3. f. 5.—. t. 
248. f. 3. Ovate, tumid, shaded off from green to yellow, rayed, 
posterior side very short; anterior obliquely curved, the extremity 
rounded. R. Serne, §'e.—Thicker and more obtuse at the extre- 
mities than Pictorum.' 
U. Cumsperzannianus. Lea. on U.2. (and Tr. Am. 6.) 
p. 25.t.7.f. 19. Elliptical, transverse, inequilateral, thin, ventral 
edge rounded ; beaks somewhat prominent, ligament short ; cuticle 
yellow with numerous subequidistant narrow greenish rays, nacre 
white and irridescent: cardinal teeth sma!l, lateral long and 
straight. +..15.—Tennessee.* 
U. Visex. Conr. N. F. W.S. 31. ¢.4.f. 3. Elliptical, ven- 
tricose, thinnish, anteriorly dilated, very oblique and arcuated, 
posteriorly rounded but angulated on the dorsal edge: ligament 
margin slightly elevated, umbonal slope rounded : cuticle yellowish 
olive, clouded with brown, anteriorly with green interrupted linear 


1 Mr. Lea in his synopsis of Uniones, (a work whose outlines are 
but filled up in the present monograph), gives as synonyms of this 
deceptive species. 
«‘U. Batavus of Fleming, Pfeiffer, Wood, Maton, Dilwyn, 
Turton—Pictorum of Montagu and of Draparnand, ¢. 11. f. 3.— 
U. Riparia and Gibba of Pfeiffer.—U. Sinuatus and Planus of 
Studer.—U. Fusculus of Muhl.—vU. Reniformis, Schmidt.—U. De- 
curvatus, Rossmasler.—U. Fuscus, Consentaneus and Amnicus 
Zieg.”—I am afraid that Mr. Leais scarcely correct in his ideas of 
our European Uniones. Assuredly the above synonyms seem to me 
so strangely united, that I have not ventured to add one iota to the 
brief description and scanty references of Lamarck. As this shell 
has been generally considered British, from trusting to the figures 
in Wood and Turton, it may be as well to observe, that I have 
reason to believe that the former was copied from Schreeter’s Fluss- 
conchylien, ¢. 3. f. 4. (and not from a British shell), whilst the 
latter is stated by Mr. Gray, to have been delineated from the 
former. 
2 Add likewise the U. Smiruu.— Gray. 
o 2 
