Explanation op Plate III. 
All the figures are of the natural size. 
Pig. 1. Mactra anserina , right valve— Cumana, Venezuela. 
,, 2. Venus superb a, right valve ,, ,, 
„ 3. Cardium eburniferum , right valve-S. Coast, Trinidad 
4a Area centrofa , right valve, interior. 
„ 4b ,, ,, right valve 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 centrota had been previously described as 
a fossil at p. 175 of the same voh (1867). 
cl. 
24 diitst 
