UNIO. 
279 
a. Anterior teeth compressed^ elevated^ sometimes 
crested, 
129. 1. Unio pictorum. Thin Painters’ Union. ^ — 
Shell oval-oblong, ventricose, produced into 
a bluntly truncated beak behind, yellowish 
green, brownish zoned, greenish behind ; 
upper edge nearly straight, lower rather 
retuse; hinge teeth very much compressed, 
arched, crenated ; hinder teeth of left valve 
small or evanescent, (t. 2. f. 11.) 
Young shell with a few isolated conical tubercles 
on the umbo. {Pfeiffer^ ii. t. 2, f. 24.) 
My a pictorum. Linn, S. Nat, ? ; Sturrn, Fauna,, vi. 2. f. a,; 
Wood,, Conch, 104. t. 19. f. 3, 4. Schroet, Flussc, t. 4. 
f. 6. — Unio pictorum. Lam, Hist, yi, 77.; Ency, Meth, 
t. 248. f. 4. ; Drop, Moll. t. 11. f. 4. ; Rossm, Icon. t. 3. 
f. 71. a, h, ; Pfeiffer,, i. t. 5. f. 9, 10. ; Leach,, Syn, Moll, 
32. a, ; Forhes and Hanley,, B, M, ii. 142. t. 39. f. 1., 
t. 2. f. 2. — Unio rostratus. Pfeiffer,, i. 114. t. 5. f. 8.; 
Alder,, Mag, Nat, Hist, ii.— Mysca pictorum. Turton Bi- 
valves, 245., Man. ed. 1. f. 11. — Unio elongatula. Pfeiffer,, 
ii. 35. t. 8. f. 5, 6. — Unio limosus. Nilson^ Moll, Suec. 110. 
— U. Deshayesii. Mich, Comp. 107. t. 16. f. 30.- — U. pon- 
derosus. Bossm. Icon, xii. 31. f. 767 — U. longirostris. Rossm, 
Icon. xi. 13. f. 738. — U. Philippi. Dup, Cat, 209., Hist, 
M, F. t. 28. f. 19. — U. curvirostris. Normand,; Ro,ss, Icon, 
f. 200. — Mya ovalis. Donn^ B, S, iv. 89. 
The old shell becomes much thicker ; and some of 
the varieties, as that called U, Philippi^ almost form 
a passage to U. tumidus, 
b. Anterior teeth conical^ high, 
130, 2. Unio tumidus. Tumid Union. — Shell ovate 
elongate, wedge-shaped, tumid, produced and 
attenuated behind, thick, brown ; lower edge 
