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 study of a quantity of material from Watlings 

 Island lagoon, collected by Prof. A. Agassiz, Dr. J. J. Brown and the U. 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 waters, 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 off 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 well-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 dominffuensis Orbigny, variety. 



Avicula atlantica Lamarck, variety. 



Melina ohliqua Lamarck, dwarfed form. 



Tellina mera Hanley, variety. 

 *Gyrena colorata Prime. 

 *Anomalocardia leptalea Dall. 



Haminea antillarum Orbigny, dwarfed. 

 *Tornatina parvipKca Dall. 



Assiminea auberiana Orbigny. 

 *CeritMum (Pyrasus)rawsoni Krebs. 

 *CerUhmm "var. degeneratum Dall. 

 *Gerithidea tenuis Pfeiffer. 



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



More recently, through the kind ofliees 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 Henriquillo. This was somewhat adulterated by 

 the presence of a number of species from the fresh water streams which fall 



