318 



Physical Geography^ etc. 



Pupa. 



The distribution shown in the foregoing list proves in a 

 marked manner the alliance of the Bahamas, and of the 

 Great Bank especially, with Cuba. The numerous repre- 

 sentatives of Polymita and of Strophia, and the ocT3urrence 

 of Polygyra, Tlielidomus and MelanieJla on the Great Bank 

 only (all three groups unrepresented iu Haiti) afford similar 

 proof, while the development of Plagioptycha iu the Turk 

 Islauds and Great Inagua,- with the fact that P. Albersiana 

 and disculus are common to them and Haiti, appears to indi- 

 cate their connection with the latter island. 



Dr. Cleve (Geology of the N. E. West India Islands, 

 Stockholm, 1871) mentions that Anegada (on the Virgin 

 Bauk) is geologically in all respects different from the other 

 Virgin Islands, that it lies northwest to southeast (the 

 others extending from west to east) aud has a close resem- 

 blance to the Bahamas. The land shells of Anegada, how- 

 ever, in common with those of the other islands on the 



* I include, for the present purpose, the foi-ms known as marglnatus and nitidulus. 

 t A single specimen in the cabinet of Mr. Ravvson, said to be from the Biminis. 



