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Guppy Reprint 
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Page g2 
posteriorly high with a decided obtuse angle formed by a 
low keel running from the umbo, on the upper and posterior 
side of which keel the shell is covered v.’ith a black 
epidermis. Valves flattened, white, rather fragile, marked 
with concentric striae of growth, which are worn smooth 
on the disk and umbones, but towards the ventral margin 
are covered with a yellowish brown wrinkled epidermis. 
Length 85, height 60, thickne.ss 30 mm. 
The details of the hinge are somewhat similar to those 
of the hinge cf Ilcnn'ivacti a giga 7 ifca ,h\:X ti e pcstcaidinal 
area resembles that of Schizodcsma. The latter feature is 
much developed in our shell, and is remarkable for its 
black epidermis, that of the other portions of the shell being 
of a light brown. M. anserina ma}' possibly be allied to the 
M. similis of Gra}’ in Beechej’’s Voyage, an Australian 
.shell, (not the J/. sbnilis of Say — ovalis Gould, which is an 
inhabitant of North America.) 
Explanation of Plate III. 
All the figures are of the yiatural size. 
P'ig. I. RTactra anserma, — Cumana, Venezuela. 
“ 2. Venus supcf'da, right valve 
‘ ‘ 3. Cardiuni ebu 7 'nifierum, right valve - S. Coast, Trinidad 
“ 4a Area centrota, right valve, interior. 
“4b “ “ right vah’e of a large specimen, 
[exterior. 
The last two species were described in the Proceedings 
of the Scientific Association of Trinidad, vol. i, 1869, pp. 
367-368. Area ce 7 itrota had been previously de.scribed as 
a fossil at p. 175 of the same vol. (1867). 
