"12 PROCEEDINGS OF PHE SCI^NPIFIC ASSOCIATION. 
as Jamaica, San Domingo and Cuba in tlio West Indies, 
and many parts of the East Indies. For a knowledge of 
these the student must consult collections and the systema- 
tic works on Conchology. Much information may however 
bo obtained from the text-books, among which I may re- 
commend Chenu’s well and amply illustrated “ Manuel de 
Conchyliologie,” although in that work the arrangement 
and definition of the groups is not always to be depended 
upon. A copy of that work may be obtained at an ex- 
tremely moderate price. Woodward’s Manual of tho 
Mollusca” is a work which may be most strongly recom- 
mended as containing much 'valuable information, its only 
fault being perhaps that its account of many of' the minor 
groups proposed by Zoologists is somewhat limited. This 
however is not always a disadvantage to the beginner. It 
will of course bo nocessary that the student of Trinidad 
■malacology should make himself acquainted with the mdl- 
lusca of cither countries in order that he may understand 
iho affinities and relations of those found in Trinidad. 
The Inosperculata form a great group which is composed 
of members obviously closely related ; but the operculato 
division consists of genera not nearly akin, and the circum- 
stance of station is almost their only connecting link. This 
is the case ’ to an extent not acknowledged in any books 
that I have met with ; but that it is a fact my researches 
into 'the lingual dentition has fully convinced me. Thus 
among the terrestrial oporculata (confining our attention to 
those of Trinidad) Adamsiella and Uelicina belong to a di- 
vision by no means closely allied to Cy clot us. Among the 
fluviatilo oporculata we have throo principal genera, Ncri- 
iina y Paludestrina, and Ampullctria , scarcely more nearly 
'related to each other than almost, any threo genera of gas- 
teropoda takon at random CHto Mdrcli has perceived 
