190 NEW-YORK FAUNA — MOLLUSCA. 
Unio VENTRICOSUS. 
Unio ventricosus. Barnes, Am. Jour. Sc. Vol. 6, p. 267, pl. 13, fig. 14. 
U. id. Say, Am. Conch. pl. 32, 
U. occidens? LEA, Trans, Am. Phil. Soc. Vol. 3, p. 435, pl. 10, fig. 16. 
Margarita (Unio) id. Ip. Ib. Vol. 6, p. 126. 
U. ventricosus. ApAMS, Amer. Journ. Science, Vol. 40, p. 276. 
Description. Shell moderately robust, subelliptical, ventricose. Beaks undulated, often 
decorticated : ligament stout. Cardinal teeth double in both valves. In one valve the exter- 
nal tooth is broad, curved and truncated above; the internal smaller and triangular; the 
lateral tooth simple, broad, and ending abruptly: in the other valve, the oblique cardinal 
teeth are placed behind each other, and both are pyramidal ; the lateral tooth deeply cleft. 
Posterior impressions confluent ; dorsal ones distinct : cavity of the beaks profound. 
Color. Epidermis olive-green, with dark green radiations; within, pure white, or white 
with a faint tinge of blue, and slightly iridescent. 
Vertical axis, 2°0; transverse ditto, 3°1. 
This species I have received from Lake Champlain, and from other waters in the western 
part of the State. It is subject to great variations in form, but its ventricose character is 
constant. 
I have adopted the synonimes of Say and Conrad, in part, in relation to this species. I 
have not, however, examined a specimen from the western waters : the figure of occzdens, as 
given by Mr. Lea, and his description coincides with that of ventricosus. 
Unio LUTEOLUS. 
PLATE XX. FIG. 241. 
(STATE COLLECTION.) 
Unio luteolus. Lam, An. sans vert. 
U. siliquoideus. Barnes, Am. Jour, Vol. 6, p. 269, pl. 13, fig. 15. 
U. inflatus. Ip. Ib. Vol. 6, p. 266. 
Margarita (Unio) luteolus. Lea, Trans. Am. Phil. Vol. 6, p. 127. 
U, inflatus. Conran, Fr. Wat. Shells, p. 69. i 
U. luteolus. Ip. Monog. pl. 10, fig. 1. 
U. id. Apams, Am. Jour. Sc. Vol. 40, p. 276. 
Description. Shell solid, oblong-ovate, moderately inflated, regularly rounded ; hinge- 
margin straight. Beaks contiguous, very slightly elevated, regularly rounded at one extre- 
mity, subangulated at the other. Surface with concentric wrinkles, becoming somewhat 
squamous at one extremity. Cardinal teeth oblique, elevated, rugose on their sides, crenate 
at tip and edges ; lateral teeth long and straight. 
Color. Epidermis yellowish olive to dark brown, with a few faint distant radiations ; within, 
varying from pearly white to bluish white, iridescent. 
Vertical axis, 1°5 — 2°2; transverse ditto, 3°0-3°5. Diameter, 0°9 —1°2, 
