34 



A M ERICAN JOl' l;X A L 



new to science, as are probably also most of the 199 undeter- 

 mined species. 



"The extraordinary dissimilarity between the fauna of the 

 Red Sea and of the Mediterranean, which has been frequently 

 remarked, and which appears to be confirmed by further re- 

 searches.on both sides of the isthmus (holding good with respect 

 to the other invertebrata and fishes as well as the Mollusca), 

 shows that a barrier between the seas must have existed from 

 very remote time; and this is not inconsistent with Prof. Issel's 

 statement that an examination of the geological conditions of 

 the isthmus leads to the conclusion that the two seas were united 

 during the Eocene and Miocene periods. 



" It is true, as has been observed by the authority I have 

 quoted, that some of the Suez species appear to be so nearly 

 related to their representatives in the Mediterranean and Atlan- 

 tic, that it is easy to suppose that they may have been originally 

 the same, and that, their distinguishing characters may have 

 !• sen acquired during the series of ages through which they may 

 hav ■ been separated, though I could hardly admit this with re- 

 spect to all the species quoted by Issel as Mediterranean equiva- 

 lents. Such species, however, form but a small percentage of 

 the whole; ami I am not sure that more remote localities, such 

 as Japan ami Australia, do not furnish about as many examples 

 of relationship to the European fauna. 



" The number of Suez species that are common to Japan, the 

 Philippine Islands, Australia, the Sandwich Islands, &c, is 

 worthy of remark, as showing that the Mollusca of the Pacific and 

 Indian oceans have a much wider distribution than those of the 

 Atlantic, where the shores of America possess but few species in 

 common with the coasts of Europe and Africa. The fact of a 

 species having in several instances been obtained from only two 

 localities very remote from each- other, such as Suez and Japan, 

 is to be attributed to (which it is a proof of) the very small amount 

 at knowledge we possess of the fauna of the intervening seas. 



'• It is not to be supposed that my present list is any near 

 approach to a, complete catalogue of the Mollusca of the Gulf of 

 Suez, much 1 'ss to those of the Red Sea, to which it forms but a 

 small contribution. Up to the very last, we never returned from 

 a day's work without having added several species to our collec- 

 tion, and we might probably have long continued to do so. It is 

 also remarkable in how many instances we obtained only one en- 

 two examples of a species." 



Mediterranean Mollusca. No. 2. By J. Gwvn Jeffreys. 



Platydia Davidsoni = Megerlia truncata (abnormal). 

 Lucina transversa, Bronn, is an Axinus. 



