144 ANATINIDA. 
pallial line simple. All the species at present known are from 
North American seas. P. claviculata, Carp. 
Myopora Gray, 1840. 
Distr.—12 sp. New Zealand, New South Wales, Philippines. 
M. striata, Quoy (evili, 50). 
Shell trigonal, rounded in front, attenuated and truncated 
behind ; right valve convex, left flat ; interior pearly ; cartilage 
narrow, triangular, between two tooth-like ridges in the left 
valve, with a free sickle-shaped ossicle; pallial line sinuated ; 
structure like Anatina; outer cells large, rather prismatic. 
Myocuama, Stutchbury, 1830. 
Distr.—5 sp. New South Wales; attached to Crassatella and 
Trigonia, in 8 fathoms water; the fry (as indicated by the um- 
bones) is free, regular, and Myodora-shaped. M. anomioides, 
Stutchb. (eviii, 51-53). M. Keppelliana, A. Ad. (eviii, 54). 
Shell inequivalve, attached by the dextral valve and modified 
by the form of the surface of attachment; posterior side attenu- 
ated; left valve gibbose; cartilage internal, between two tooth- 
like projections in each valve, and furnished with a movable 
ossicle; anterior muscular impression curved, posterior rounded, 
pallial sinus small. 
Animal with mantle-lobes united; pedal opening and siphon 
surrounded by separate areas; siphons distinct, unequal, small, 
slightly fringed ; a minute fourth orifice close to the base of the 
branchial siphon; visceral mass large, foot small and conical ; 
mouth rather large, upper lip: hood-like; palpi tapering, few- 
plaited ; gills one on each side, triangular, plaited, divided by 
an oblique line into two portions; excurrent channels four, two 
at the base of the gills and two below the dorsal lamine. 
( Thracie.) 
ASTHENOTHARUS, Carpenter, 1864. 
Disir.—A. villosior, Carp. Cape St. Lucas, L. Cal. 
Shell like Thracia, hinge without teeth, spongy cartilage situ- 
ated in a pit under the umbones, 
TuHrRaActA (Leach), Blainville, 1824. 
Syn. —Odoncinetus, Costa. ea Herm. COorymya, 
Agassiz. © 
“Distr.— 21 sp. Greeniandy United States, Norway, Britain, 
Mediterranean, Canaries, China, Sooloo; 4-110 fathoms. Fossil, 
36 sp. (Trias 7) Lower Oolite— ; United States, Australia, 
Europe. 7. pubescens, Pult. (eviii, 55). Z. plicata, Desh. 
(eviii, 56). 
