obtained in the Gulf of Suez. "5491 
In my list of named species will be found about 355 not 
previously recorded as inhabiting the Red Sea; of these, 
53, including 3 genera, are new to science, and have been 
described by Mr. Henry and Mr. Arthur Adams. Also most 
of the undetermined species will probably prove to be new, 
and all of them additions to the Red-Sea fauna. 
Prof. Issel, of Genoa, has recently published a work upon 
the shells of the Red Sea, in which he enumerates 640 species 
of recent Mollusca as all that are recorded from that district. 
His list includes about 100 new species described by himself, 
some of which had been previously figured, but not named or 
described, by Savigny in the ‘ Description de l'Egypte. As 
he has inserted species upon the faith of various authors, it is 
probable that there are some inaccuracies in his catalogue, as 
in the case of Nassa circumcincta, which appears to be included 
on the authority of Reeve. Not only did I not obtain this 
species in the Gulf of Suez, but I did find it in the Mediterra- 
nean, on the coast of Syria, in company with N. gibbosula, 
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 re- 
spect to the other Invertebrata and fishes as well as the Mol- 
lusca), 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 condi- 
tions of the isthmus leads to the conclusion that the two seas 
? 
admit this with respect to all the species quoted by Issel as 
Mediterranean equivalents. Such species, however, form but 
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 pone ut few 
