“I 
Or 
TRIBE NAYADES. 7G 
Section B.—Non-SyMpHONOTE. 
* Plicated. 
U. Nicxurnianus. Lea. Tr. Am. Ph. 5. t. 1. Subtriangular, 
inequilateral, very thick, oblique, very much spread out, with an 
elevated wing, flattened towards the beaks, very much undulated 
even to the point of the beak (except near the anterior and ventral 
edges) ; cuticle dark brown, nacre pearly white ; teeth very thick, 
the lateralcurved. 5..54.—China? 
U. Caratus. Conr. N. F.W.S. of Am. p. 29.t.3. f. 4. 
Subtriangular, very inequilateral, rough, much compressed, with a 
broad furrow from the beaks to the base, (except the umbo and 
posteriorly), covered with small irregular interrupted undulations 
which are profound behind the umbonal slope, with distant slight 
concentric grooves; umbones much flattened, beaks prominent ; 
cuticle dark olive, obscurely rayed, nacre white and irridescent : 
teeth thick.—T'ennessee. 
U. Heros. Say.—U. Mututipricatus. Lea. on U. 1. 
p. 80. t. 4. f. 2.—U. Ligamentinus. (old) Lam?—Unov- 
tatus. Say. Am. Con. t. 16. Trapezoidal, inequivalve, trans- 
verse, compressed ventrally and anteriorly, very thick, adorned 
except posteriorly with broad undulations diverging from the um- 
bonal slope, those near the carinated dorsal edge curving towards 
it; beaks slightly prominent, the umbones flattened: ligament 
large long and curved ; cuticle black and much wrinkled, nacre 
pearly white and irridescent : cardinal teeth thick, lateral long and 
curved. 34..53.—Ohi. 
U. Unputatus. Barnes. in Sil. J. 6. t. 2. f. 2.—U. Cos- 
ratus. Conr. Mon. U.t.7. Rhombic-ovate, thick, with nume- 
rous large waving oblique folds (except on the posterior side which 
is very short obtusely rounded and merely marked by the transverse 
wrinkles which become lamellar anteriorly); cuticle blackish 
brown; nacre pearly white, irregularly spotted with brownish 
green; ventral edge little arcuated, not incurved: beaks not 
prominent, eroded: cardinal teeth very thick, direct, sulcated. 
32. .43.—Ohio. 
U. Puicatus. Say. in Ency. Amer.—Barnes. § Hildr. in 
Sil. J.—U. Peruviana. Lam. 4.—Rarapuicata. Lam. 5.— 
DomperAna. Valen. in Humboldt. Voy.—U. Unpoutatus & 
Muttipiicatus. Desh. Suboval, thick, ponderous, with two or 
three more conspicuous undulations, which are profound very 
oblique continued to the anterior ventral edge and not arising 
from the decorticated umbo : nacre pearly. 
