BULLETIN OE THE UNITED STATES FISH COMMISSION. 
356 
Using the common colloquial designations, there are 16 fresh-water shells, 102 
land gastropods, and of marine mollusks, including the Auriculacea and Trunca- 
tellidoi. 535 species identified in this report. 
The absence of Pulmonata petrophila is noticeable, but they undoubtedly exist, 
and will hereafter be detected on the shores of Porto Rico. The number of Nudi- 
branchs is probably large, but, as in many other regions, they have not been collected 
and are therefore unknown. To some extent the same is probably true of the 
Cephalopods and Tectibranchs, while the census of the land and fresh-water shells is 
probably nearly complete. In Gundlach’s list 212 marine species were enumerated, 
to which the researches of the United States Fish Commission now add 323, consider- 
ably more than doubling the number reported from Porto Rico, but no additions are 
made to the land shells enumerated in Crosse’s catalogue. 
The West Indies and Bahamas form a great conchological region, which is richer 
in species of land snails than any other area of equal size on the globe. The entire 
archipelago is estimated to contain about 95,000 square miles, and within it there are 
known something like 2.000 species of land and fresh-water mollusks. Of these less 
than a hundred are fresh-water forms. 
The island of Cuba, with an area of 11,655 square miles, has nearly 700 species of 
land and fresh- water mollusks; Haiti, with 28,219 square miles, and which is not at 
all thoroughly explored, has about 270 species; Jamaica, with some 1,207 square miles, 
has not less than 500 species, and Porto Rico, with an area of 3,550 square miles, con- 
tains about 130 species. This region has been divided into a number of subregions 
by Fischer as follows: (1) Bahamas; (2) Cuba and the Isle of Pines; (3) Jamaica; (1) 
Haiti and Navassa: (5) Porto Rico, Vieques, St. Croix, St. Thomas, St. Johns, Tortola, 
Anguilla, St. Martin, St. Bartholomew, and Sombrero; (6) Guadeloupe, Martinique, 
Dominica, St. Christopher, Antigua; (7) St. Vincent, St. Lucia, Barbados, Grenada, 
Trinidad; (8) Windward Islands. Curasao, Buen Ay re. 1 
While each of the four great islands Cuba, Haiti, Porto Rico, and Jamaica, and 
the groups of smaller islands given above, forms to some extent a subfauna, there is 
evidently a close relation between the faunas of these four islands and their small 
island dependencies, as far south as the Anegada Channel, and of the Bahamas. The 
character of the mollusks found to the south of this channel, which carries through a 
depth of not less than 900 fathoms, is markedly different and more South American 
in its relations. 2 
The northern part of the Lesser Antillean Chain is of volcanic origin, and is prob- 
ably much more recent than the Greater Antillean Islands. While a few stragglers 
may have passed from the northern islands to the southeastern ones, it is not unlikely 
that there has been no land connection across the Anegada Channel within the period 
of the existing West Indian land-moll usk fauna. 
One of the remarkable features of this fauna is the large proportion of oper- 
culated land mollusks. There are within this area not less than 600 species of these, 
or 30 per cent of the entire fauna. In Cuba and Jamaica they form one-half of the 
land-snail fauna, but only about one-fourth of that of Porto Rico. 
1 Manuel de Conchyliologie, p. 269. These divisions are founded in part, on the studies of Bland. 
2 See Distribution and Classification of the Land and Fresh-water Mollusks of the West Indian Region, Proc. IT. s. 
National Museum, xvil, pp. 424 and 443, 1394. 
