On a new Speciea of Phreatoicusyrowi Tasmania. 349 



XXXVIII. — On a nero Species of 'Phrcatoicus from Tasmania. 

 By George M. Thomson, F.L.S., Coir. Mem. Roy. Soc. 

 of Tasmania. 



[riate XI.] 



The specimens described in the followini^ paper were received 

 from Mr. Aucr^istus Simson, of Launceston, who collected 

 them in the Great Lake, Tasmania. This lake lies at an 

 elevation of about 38S0 feet above sea-level. Mr. Simson 

 was unfortunately unprovided at the time with suitable 

 material or apparatus for preserving Crustacea ; conse- 

 quently the specimens were put away to diy, and reached 

 me in a more or less mutilated condition. 



In a paper on Tasmanian Crustacea* published in the 

 last volume of the Proc. Roy. Soc. Tasm. p. 76, I men- 

 tioned havino; found among specimens taken on the summit 

 of Mount Wellington a single example of P. australis, 

 Chilton. There is little doubt that the specimen referred to 

 was merely a young form of the present species. I find that 

 the young of P. tasmanim resemble the adult form of P. aus- 

 tralis in the comparative smoothness of the body and the 

 shortness of the telson, while the adults are very distinct, 

 their body being so characteristically spinose and the uropods 

 80 much longer. 



The occurrence of the three forms of this peculiar genus in 

 the three adjacent and yet widely separated regions of New 

 Zealand, South-east Australia, and Tasmania is of great 

 interest from a geographical point of view; but beyond 

 recording the fact it is not safe as yet to generalize on 

 it, as very little is known concerning the crustacean fresh- 

 water fauna of any of these countries. 



The following is a description of this very distinct form : — 



Phreatoicus tasmanicej sp. n. 



Surface of body in the adult specimens more or less 

 covered with acute spines and tubercles, which, on the head 

 and thoracic portion of the body, are particularly numerous on 

 the dorsal surface, and are arranged in two or three rows 

 crossing the segments from side to side. In the abdominal 

 segments they are most abundant on the margins. Tlie 

 females are somewhat smaller and less spinose than the males, 



* ' Papers and Proceedings of the Royal Society of Tasmania ' for 1892, 

 p. 45. 



