_Porto Rico_, with Vièque, is practically a fragment of San Domingo. The points of close relationship are the occurrence of _Caracolus_, _Cepolis_, and _Parthena_ among the Helicidae, and of _Simpulopsis_, _Pseudobalea_, and _Stoastoma_. _Cylindrella_ and _Macroceramus_ are but poorly represented, but _Strophia_ still occurs. The land operculates (see the Table) show equal signs of removal from the headquarters of development. _Megalomastoma_, however, has some striking forms. The appearance of a single _Clausilia_, whose nearest relations are in the northern Andes, is very remarkable. _Gaeotis_, which is allied to _Peltella_ (Ecuador only), is peculiar. [Illustration: FIG. 231.--Examples of West Indian Helices: =A=, _Helix_ (_Parthena_) _angulata_ Fér., Porto Rico; =B=, _Helix_ (_Thelidomus_) _lima_ Fér., Vièque; =C=, _Helix_ (_Dentellaria_) _nux denticulata_ Chem., Martinique.] _Land Mollusca of the Greater Antilles_ Cuba. Jamaica. S. Domingo. Porto Rico. Glandina 18 24 15 8 Streptostyla 4 ... 2 ... Volutaxis ... 11 (?) 1 ... Selenites 1 ... ... ... Hyalinia 4 11 5 6 Patula 5 1 ... ... Sagda ... 13 2 ... Microphysa 7 18 8 3 Cysticopsis 9 6 ... ... Hygromia (?) ... ... 3 ... Leptaxis (?) ... ... 1 ... Polygyra 2 ... ... ... Jeanerettia 6 ... ... 1 Euclasta ... ... ... 4 Plagioptycha ... ... 14 2 Strobila ... 1 ... ... Dialeuca ... 1 ... ... Leptoloma 1 8 ... ... Eurycampta 4 ... ... ... Coryda 7 ... ... ... Thelidomus 15 3 ... 3 Eurycratera ... ... 7 ... Parthena ... ... 2 2 Cepolis ... ... 3 1 Caracolus 8 ... 6 2 Polydontes 3 ... ... 1 Hemitrochus 12 1 ... ... Polymita 5 ... ... ... Pleurodonta ... 34 ... ... Inc. sed. 5 ... ... ... Simpulopsis ... ... 1 1 Bulimulus 3 3 6 7 Orthalicus 1 1 ... ... Liguus 3 ... 1 ... Gaeotis ... ... ... 3 Pineria 2 ... ...