92 PROCEEDINGS OP THE SCIENTIFIC ASSOCIATION, 
posteriorly high with a decided obtuse angle formed by & 
low keel running from the umbo, on the upper and posterior 
side of which keel the shell is covered with a black 
epidermis. Valves flattened, white, rather fragile, marked 
with concentric striae of growth, which are worn smooth 
on the disk and unibones, but towards the ventral margin 
are covered with a yellowish brown wrinkled epidermis. 
Length 85, height 60, thickness 30 mm. 
The details of the hinge are somewhat similar to those 
of the hinge of Uemimaclra gigantea , but the postcarinal 
area resembles that of Schizodesma . 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 may possibly be allied to the 
M. similis of Gray in Beech ey’s Voyage, an Australian 
shell (not the M. similis of Sav=ovalis Gould, which is an 
inhabitant of North America.) 
Rules and Regulations and List of Members of the 
Scientific Association of Trinidad — 1873-74. 
The object of this Association is the cultivation of Scientific 
Knowledge in the West Indies. 
rules: 
1. This Association shall be called the “ Scientific Asso- 
ciation of Trinidad. ” 
2. The objects of the Association shall be carried out 
by the reading of papers and the discussion of Scientific 
subjects, by maintaining a correspondence with scientific 
men in other countries, by assisting in the development 
