THE BAHAMA ISLANDS 45 



THE FAUNA OF THE " SALT PANS." 



The fauna of the hypersaline pans or lagoons is perhaps worth a few 

 paragraphs of comment. 



In 1894 the writer made a stud}' of a quantity of material from Watlings 

 Island lagoon, collected by Prof. A. Agassiz, Dr. J. J. Brown and the IT. S. Fish 

 Commission. This comprised species living in the highly saline waters of the 

 lagoon and others which frequent the dry land on its borders, both being 

 mingled in the drift on the shores of the lagoon. Several species were found 

 to be characteristic of the lagoon Avaters, though probably all its population was 

 derived from species ordinarily frequenting the shallow water of the sea adja- 

 cent to the shores of the island, and which, notwithstanding the gradual increase 

 in salinity after the lagoon was cut oif from the free access of sea water, had 

 managed to survive. These species under the peculiar conditions in which they 

 were then placed became modified until several of them developed Avell-marked 

 specific differences. 



The changes to which they were subjected appear to have been an increase 

 in the salinity and consequently in the specific gravity of the water; higher 

 temperature; and greater exposure to sunlight. 



All the lagoon species as compared with their nearest allies exhibited 

 certain common differences; these were tenuity of shell, diminutive size, and 

 intensification of color when the species was other than black or white. These 

 differences may reasonably be ascribed to the new conditions operating upon all 

 the species exposed to them. The list is as follows : 



Mytilus dominguensis Orbigny, variety. 



Avicula atlantica Lamarck, variety. 



Melina ohJiqua Lamarck, dwarfed form. 



Tellina mera Hanley, variety. 

 *Cyrena colorata Prime. 

 *Anomalocar(lia leptalea Dall. 



Haminea antillarum Orbigny, dwarfed. 

 *Tornatina parviplica DalL 



Assiminea auheriana Orbigny. 

 *GeritMum (Pyrazus) rmvsoni Krehs. 

 *Cerithiitm var. clegeneratuvi DalL 

 *Cerithidea tenuis Pfeiffer. 



The species preceded by an asterisk are peculiar to the lagoons. 



More recently, through the kind offices of Mr. C. Lyon Hall and Mr. E. 

 Furbush of Port au Prince, Haiti, I obtained a lot of material from the great 

 salt lagoon known as Lake Henri qui llo. This was somewhat adulterated by 

 the presence of a number of species from the fre.sh water streams which fall 



