306 DISTRIBUTION AND .ETIOLOGY OF THE CRAYFISHES. 



is found, along with other blind animals, in the sub- 

 terranean caves of Kentucky. 



All the crayfishes of the northern hemisphere belong 

 to the Potamobiida, and no members of this family are 

 known to exist south of the equator. The crayfishes of the 

 southern hemisphere, in fact, all belong to the division of 

 the Parastacidce, and in respect of the number and variety 

 of forms and the size which they reach, the head-quarters 

 of the Parastacidce is the continent of Australia. Some 

 of the Australian crayfishes (fig. 76) attain a foot or 

 more in length, and are as large as full-sized lobsters. 

 The genus Engam of Tasmania comprises small cray- 

 fish which, like some of the Cambari, live habitually on 

 land, in burrows which they excavate in the soil. 



New Zealand has a peculiar genus of crayfishes, 

 Paranephrops, a species of which is found in the Fiji 

 Islands, but none are known to occur elsewhere in 

 Polynesia. 



Two kinds of crayfish have been obtained in southern 

 Brazil, and have been described by Dr. v. Martens,* as 

 A. pilimanus and A. brasiliensis. I have shown that 

 they belong to a peculiar genus, Parastacus. The former 

 was procured at Porto Alegre, which is situated in 30 

 S. Latitude, close to the mouth of the Jacuhy, at the 

 north end of the great Laguna do Patos, which communi- 



* Siidbrasilische Suss- und Brackwasser Crustaceen, nach den Samm 

 lungen des Dr. Keinh. Hensel. Archiv. fiir Naturgeschichte, xxxv, 

 1869. 



