FRESHWATER CRUSTACEA OF TASMANIA. 69 



therefore that Lepklurits has reached Australia hy way of S. America and Antarctica, 

 while Apus entered by way of the Asiatic tropics. 



The evidence of an Antarctic connection between New Zealand, Southern Australia, 

 and South America, derived from a consideration of the freshwater Crustacea of Tasmania, 

 is thus particularly cogent, because we are dealing with a group of animals whose distri- 

 bution is closely dependent on temperature, and unless we are to suppose that tropical 

 Asia and Australia have in the not very distant past possessed a totally different climate 

 and physical character from their present condition, it is impossible to conceive that these 

 essentially temperate and for the most part alpine creatures have reached their present 

 isolated position in Tasmania by this route. 



And when we take into consideration the fact that the freshwater fish of Tasmania 

 (Galaxias, Prototroctes, and Apliritis), the Mollusca for the most part, and the most 

 typical of the Alpine trees {e. g. the two species of Fagus, F. Cunninghamii and F. Guiinii) 

 have their closest allies in one or more of the countries of the temperate Southern 

 Hemisphere, we are forced back on the existence in the past of a land-connection, 

 probably, as Mr. C. Hedley originally suggested (Ann. Mag. Nat. Hist. (6) xvii. 1896, 

 p. 113), by means of rays of land passing southwards to meet an antarctic continent, 

 uniting these southern lands, which at the present time are separated by so vast and so 

 deep stretches of ocean. 



Part II.— SYSTEMATIC. 



Subclass MALACOSTBACA. 



With the exception of the Isopods and Amphipods, it is not proposed here to give 

 a systematic description of the Malacostraca, as they have either been described else- 

 where or else will form the subject of future memoirs ("A Monograph of the Anaspi- 

 dacea," in preparation for the Quarterly Journal of Microscopical Science; and "The 

 Cra) fishes of Australia and Tasmania," in preparation for the Memoirs of the Melbourne 

 Museum). A sufficient account of tliem will be given, however, to facilitate their 

 recognition. 



Order DECAPODA. 



Family Atyidj:. 



Genus Xiphocaris. 



Xiphocaris compressa, v. Mart. 



This freshwater prawn is very abundant in those streams of Tasmania which are 

 discoloured by flowing over the sandstones, e. g. the Clyde and Jordan Rivers, and also in 

 some of the lakes with similar cloudy water, e.g. Lakes Sorell and Crescent and Tiberias 

 Swamp. It is a widely ranging species, extending into Victoria, New South Wales, and 

 Queensland. As no other prawn occurs in the freshwaters of Tasmania, it is unnecessary 

 to give a description of this species. 



SECOND SERIES. — ZOOLOGY, VOL. XI. 10 



