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. {^Pfeiffer, ii. t. 2. f. 25.) 
Unio tumid iis. Retzius, Nov. Gen. 17. n. 3. ; Forhes 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. Z>., ii. 27., and 
t. 14. f. 202, 203, 204. — Mya ovalis. Pulieney, Dorset. 27. 
— Unio ovalis. Leach., Syn. Moll. 344.; Flem. B. A. 416. — 
Mysea solida. Turton^ Bivalves^ 246. t. 16. f. 2., Man. 
ed. 1. 22. f. 13. — Mya ovata. Donovan^ iv. t. 122. — Unio 
inflata. Hec. Moll. Valenc.i. 148. — U. Michaudiana. Des 
Moul. Act. Soc. Bow'd, 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. 
