BROWN : LAND AND FRESHWATER SHELLS OF BARBADOS. 267 



probably of the Baltic, and its introduction into Barbados is not yet 

 accounted for. As stated above, Limncea aibensis var. must be con- 

 sidered peculiar to Barbados, as will be seen by the remarks of Mr. 

 Chas. T. Simpson, of Washington, who kindly identified it and 

 compared it witli specimens in the United States National Museum 

 (see page 271). The remaining species, Platiorbis ad trains and P. cir- 

 cumlineatus, have doubtless been introduced from St. Vincent or some 

 of the other neighbouring Islands. The former has been found in 

 several pools in different localities: the dispersal of many varieties is 

 doubtless attributable to direct personal agency, as living plants are 

 continually being imported from the neighbouring colonies ; more- 

 over, large numbers of water birds resort to our pools and swamps 

 annually from the delta of the Mississippi and Florida, and visiting, 

 as they do, some of the islands in transit may be responsible for the 

 introduction of new freshwater species. 



The relationship of the fauna of Barbados is plainly set forth in 

 the accompanying table, and a reference to that will prove interesting. 

 It will be seen that sixteen of the species are found in Trinidad, 

 fourteen in St. Vincent, seventeen in Cuba, twelve in Grenada, ten in 

 Guadeloupe, eight in Dominica, and six in St. Lucia and five in 

 Martinique, whilst twelve are found in di^erent parts of South 

 America. Three species, Suhulina odona, Opeas beckiana and Lepti- 

 naria lamellata are common to nearly all the West Indies and portions 

 of South iVmerica also. One species, Vitrea implicatis, is found only 

 south of Barbados, whilst eleven are only found north of this island. 

 At present it would be unwise to draw any general conclusions as to 

 the distribution of the land shells throughout the West Indies and 

 South America, as the northern or lesser islands have been so little 

 worked. 



Reference has been made to the distinct colour-forms in Pleuro- 

 donie Isabella^ Bulimulus exilis and Neritina virginea as in each case 

 the markings are so very distinct that record should be kept of them. 

 In the case of P. Isabella the horn-coloured and white-lipped variety 

 has been met with in only one gully, mixed with typical species, but 

 the varietal forms of Bulimulus exilis are met with all over this 

 island and the other islands as well. A type collection of nearly all 

 the species enumerated has been placed in the recently-formed 

 Museum attached to the Barbados Natural History Society. 



In conclusion, the author desires to place on record his appreciation 

 of the great encouragement he has received from Mr, W. Moss, who 

 also enlisted the aid of Mr. Edgar A. Smith and Mr. J. H. Ponsonby 

 in the determination of the specimens. His thanks are further due 

 to Mr. Smith for kindly revising the manuscript, and for the interest 

 he has shown in the publication of these notes. 



