17 
rugose, like the auterior lateral tooth of Venus; the hinder of left 
valve very thin, compressed ; the middle of right valve compressed ; 
the hinder very broad, with a deep groove; anterior lateral tooth 
none; hinder of right valve compressed, separated from the dorsal 
margin by a deep groove. Siphonal infiection none, or very slightly 
truncate. Mantle lobes free beneath. Siphons very short. 
1. CyPRINA. 
1. C. islandiea, t. 316. f. 4, t. 316a. f. 2. 
Fam. 3. Glauconomide. 
Mantle lobes united. Siphons elongate, united at the base. 
Pedal opening small, linear. Foot small, compressed in front. 
Palpi triangular, elongate. Gills elongate, united behind, but not 
produced. Shell oblong, covered with a hard olive periostraca ex- 
tending beyond the edge. Lateral teeth none. 
1. GLAUCONOME. 
1. G. chinensis (fig. 2). 
Fig. 2.—Glauconome chinensis. 
pp, pedal muscles. 7, retractor of siphon. — s, siphon retracted. 
e-6, pedal aperture. aa’, adductor muscles. 
Fam. 4. Petricolide. 
Siphons elongate, separate nearly to the base. Aperture ciliated. 
Pedal opening small. Foot small, thin, cylindrical, with a distinct 
byssus. Shell ovate. Cardinal teeth bent up, as if coming from 
the inner surface of the shell under the umbo. 
1. Perrico.a. 
1. P. striata, t. 322. f. 4. 
2. P. Lithophaga, t. 322. f. 1, 5. 
3. P. hyalina, t. 322. f. 5. 
4. P. patagoniea, t. 322. f. 2. 
Fam. 5. Corbiculade. 
Mantle lobes free. Pedal opening very large. Hinder end 
double-edged. Siphonal apertures distinct ; anal small; inhalent 
VOL. V. Cc 
