334 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



Islands on the northern side of the Caribbean Sea. It ap- 

 pears that no less than fifteen species are common to the 

 Great Bank and Cuba, of which nine occur also in Florida, 

 while the more easterly of the Bahamas (Turk Islands and 

 Inagua) have, in common with Cuba, four species only. The 

 latter islands, the distribution both of genera and character- 

 istic species considered, are proved to have relations with 

 Hayti rather than Cuba. 



One species of a genus {Polygyra)^ which has its chief de- 

 velopment in the Southern States, is found in Bermuda as 

 well as in certain of the islands on the Great Bahama Bank. 



In a former paper Mr. Bland argued, from the distribution 

 of the land shells, that the West India Islands on the eastern 

 side of the Caribbean Sea (from Trinidad to the Antigua Bank) 

 are the remains of an ancient northerly prolongation of the 

 South American continent. In the present paper he contrib- 

 utes evidence in suj^port of the suggestion of Professor Dana, 

 that the peninsula of Florida, Cuba (with the islands to the 

 eastward of it), and the Bahamas, all were once a part of a 

 greater Florida, or southeastern prolongation of the North 

 American continent. 



ON THE NATURE OF APTYCHUS. 



As is well known to paleontologists, the fossil remains 

 known as Aptychi have of late been almost universally con- 

 ceded to be in some way connected with Ammonites^ but 

 whether as opercula, jaws, or otherwise, has been in dispute. 

 Some excellent naturalists have adopted the belief that they 

 represented the jaws of the living Nautili;' since, on the one 

 hand, they had a general correspondence with the jaws, and, 

 on the other hand, the nautili had no other hard parts at all 

 analogous to them. But of late the proofs of their belong- 

 ing to some other part of the organization have accumulated, 

 and it has recently been urged, with a strong degree of prob- 

 ability, that they were closely connected with the nidament- 

 ary glands in the female Nautilus, and in reality constituting 

 protecting organs of those glands. This view, first enuncia- 

 ted by the late Professor Keferstein, has been strongly sup- 

 ported by Zittel, Waagen, and Favre, and has the merit of 

 being based on a comparison with the structures of the re- 

 cent Nautilus. Although, as already remarked, there are no 



