1853.] 261 
Plect. crassidens. 
U. crassidens,* (a) Lam., An. sans Vert. vi. 71. 
interruptus, Say., Transylvania Journ., 1831, iv. 525. 
Amer. Conch. pl. 33. 
trapezoides, Lea, 1838, vi. 69, 3, 1, Synopsis, 21. 
Chenu, Conchyl. Unio, pl. 28, fig. 6. 
Nicklinianus. 
U. Nickiinianus, Zea, v.28,1,1, Synopsis, 19. 
perplicatus, Cov. Proc. Acad. Nat. Sc. 2d ser. i. 19. 
Journ. Acad. Nat. Sc. ii. 276, 38, 2. 
U. atrocostatus, Lea, Aug. 1845, x. 70, 2,15, Synopsis, 20. 
*plectophorus, Coz. Journ. Acad. Nat. Sc. i. 2d ser. 277, 38, 7. 
plicatus. 
U. plicatus, Say, Nicholson’s Enc., article Conch. iv. 
Barnes, Sillim. Journ. vi. 120, 3, 3. 
Lea, Synopsis, 20. 
U. Peruviana, Lam., An. sans Vert. vi. 71. 
Enc. Method. pl. 248, fig. 7. 
U. rariplicata, Lam., vi. 71. Desh. ed. of Lam. v. 533. 
Dombeyanus, Valdene. 
undulatus, Desh. (not Barnes) ed. of Lam. vi. 533. 
multiplicatus, Desh. (not Lea) ib. Vi. 533. 
crassus, Barnes, Sillim. Journ. vi. 118, 1, 1. 
plicata, Swains., Malac. 271, 54,c. 
Hippopeus, Lea, 1845, x. 68, 1,1. 
Sloatianus. 
U. Sloatianus, Lea, viii. 217, 16, 33, Synopsis, 21. 
Chenu, Conchyl. Unio, pl. 32, fig. 7. 
U. plectophorus ? Con. 
CoMPLANARIA, Swains., Agas. 
Comp. complanata. 
& Alas. complanata, Barnes, Sillim. Journ. vi. 278, 13, 22. 
Hild. ibid. Xiv. 289, 
Symphynota complanata, Lea, ili. 448. 
U. complanata, Desh. ed. of Lam. vi. 559. 
Katherina, Lea, Synopsis, 42. 
costata. 
Alasmidonta costata, Raf., Ann. v.52, 82,15, Poulson’s Trans. 63. 
Alasmodonta rugosa, Barnes, Sillim. Journ. vi. 278, 13, 21. 
Complanaria rugosa, Agas. Stimpson’s Shells of New Eng. 14. 
compressa. 
Symphynota compressa, Lea, 1832, iil. 450, 12, 22. 
U. compressus, Con. Monog. 71, 40, 1. 
Dekay, Zool. of New York, 191, 21, 245. 
Lea, Synopsis, 19. 
Complanaria alasmodontina, Stimpson, Shells of New Eng. 14. 
* This species is identical with the zxterraptus of Say and trapezordes of Lea. 
The description “ antice binis ternisve subsinuosa,’’? can apply to no other 
species which could be compared with Say’s izterruptus. This description 
applies to (@) of Lam., which Mr. Lea acknowledges to be his trapezotdes, 
and is the type of crassidens. How, then, can he set it aside, and take up 4 
as the type of that species, especially as it does not agree with the description? 
