124 OPEAS. 



the last whorl carinate. All other forms have the whorls 

 rounded. 



The species are grouped geographically, thus: 

 I. Generally distributed, colonizing species, no. 1 to 4. 



II. West African, no. 5 to 14. 



III. East African, no. 15 to 21. 



IV. South African, no. 22 to 26. 



V. Species of the Comoro, Mascarene and other East 



African islands, no. 27 to 34. 

 VI. Species of Southeastern Asia, Ceylon to Tonkin, no. 



35 to 43. 



VII. Chinese species, no. 44 to 68. 

 VIII. Japanese Empire, no. 69 to 71. 

 IX. East Indian species, Nicobar Is. to New Caledonia, 



no. 72 to 80. 



X. Philippine and Caroline species, no. 81 to 90. 

 XI. Polynesian and Micronesian species, no. 91 to 93. 

 (Australian species, see Pseudopeas}. 



I. Generally distributed species. 



Several species of Opeas in each hemisphere have been en- 

 abled, by their hardiness and adaptability to life in culti- 

 vated areas, to colonize over a large part of the tropical and 

 subtropical zones. There cannot be much doubt that the car- 

 riage of living plants from place to place has been a chief fac- 

 tor in the dispersal of Opeas, and of Subulina octona, Val- 

 lonia, Agrolimax l&vis and other snails as well. The habits 

 of these forms are such that they find practically the same 

 environment anywhere in zones of similar temperature, and 

 their spread from new centers is often very rapid. Opeas 

 gracile is probably the most widely distributed land snail in 

 the world. 



Three American species have been introduced into the Old 

 World: 0. goodalli Mill., frequently found in English hot- 

 houses, and acclimated in Rodriguez, the Cape Verde and 

 Hawaiian Islands, and 0. swiftianum Pfr. and micra Orb. in 

 Mauritius, where they were taken by Nevil]. 



In some islands the whole Stenogyrine fauna has apparently 



