MOLLUSCA. 
169 
the operculated land-shells are common to the continent and the 
islands, two peculiar to the continent, and ten to the islands. 
Regarding species, four only are common to both, but about 
600 peculiar to the islands, and only about 150 to the continent. 
The zoological province of the West Indies may he divided into 
five suhprovinces : — 
1. Cuba, with the Bahamas and Bermudas. Diplopoma is exclusively 
peculiar, Megalomastoma, Choanopoma^ Ctenopoma, Cistula, (JJiondropomay 
Trochatclla, and IlcUcina are well represented. A foramen in the superior 
margin of the aperture is found in many Cuban species of several genera of 
Cyclostomid(B, but not in one species from any of the other islands. Chon^ 
dropoma dentatum and Helicina suhglohulosa are common to these islands and 
the continent (Florida). 
2. Jamaica. The genera Geomelania, Chittya, and Jamaicia are peculiar, 
Stoastoma (with 8Q species) and Lucidella nearly so. No Megalomastoma or 
Chondropoma. No species in common with the continent. 
3. Haiti. No peculiar genus. Megalomastoma, Licina, and Chcmdropoma 
in common witli Cuba, Stoastoma and Lucidella with Jamaica. 
4. Porto Rico, with Vi^qiio, the Virgin Islands, Anguilla, and St. Bartho- 
lomew. No peculiar genus. 3Iegalomastoma and Chondropoma are repre- 
sented, indicating a nearer alliance with Cuba and Haiti than with Jamaica ; 
but there are wanting Cyclotus, Ctenopoma, and Trochatclla. No species in 
common with the continent, but a rather large number of species common 
with the several islands of this subprovince. 
5. Guadaloupe, Martinique, and Trinidad, with the adjacent islands. 
No genus exclusively peculiar ; but Cyclophorus, which is not found in the 
other subprovinces, is common to this and the continent of Southern Ame- 
rica, and even to Asia. No Megalomastoma, and only one species of the 
subfamily Licinea. Cyclotus translucidus and Helicina dysoni common to 
Trinidad and the continent (Venezuela and even Honduras). 
Eland, Th. Remarks on the Distribution of the Inoperculatecl 
Land- shells which inhabit the Continent of America and 
the West Indies. Am. Journ. Conch, ii. pp. 349-370. 
The genus Helix predominates in North America, Bidimus (with BuU- 
mulus) in Sdutli America, and Cylindrella in the West Indies. The closer 
relations of the subprovinces embracing Cuba, Jamaica, and Haiti to 
North America, and of the Porto Rico and Guadaloupe subprovinces to 
South America, are shown by the greater numerical representation of Helix 
in the former, and of Bulimus in the latter. The development of these two 
genera is more nearly balanced in Mexico and Central America. Cylindrella, 
Oleacina {Glandind), and Spiraxis are copiously represented in Mexico and 
Central America on the continent, in Cuba, Jamaica, and Haiti among 
the islands, but feebly represented in the Porto Rico and Guadaloupe sub- 
provinces, as well as on the continent of South America. The subgenera of 
Helix most characteristic of Cuba are : — Eurycampta {IL honplandi), Coryda 
{H. alauda), Thelidomus (^H. auricomd), Polymita (7£. muscaruni), Polydontes 
(7T. imperator'), and Caracolus (H. sagemon). Those of Haiti: — Cysticopsis 
{H. tenerrima), Pleurodonta (H. lucerna, soror, sinuatd), and Leptoloma 
{H. fuscocincta) j the genus Sagda is almost peculiar to Jamaica, The pecu- 
