2 A KEVISIOX OF THE ASTACID.E. 



appendages of male transformed into ,st\ liform organs, or else absent ; 

 external branch of posterior pair of appendages divided by a transverse 

 sutnre; gills composed of a stem beset with numerous cjlindi'ical filaments 

 (trichobranchioe), those borne on the proximal segments of the thoracic 

 appendages (podobranchiaj) imperfectly, or not at all, separated into a 

 proper branchi.al and a lamellar portion; jnst in front of the base of tiie 

 podobranchias a pencil of long, fine seta? (coxopoditic seta}) arises from a, 

 small papilla on the proximal segment of the legs. 



Huxley has shown, in his essay " On the Classification and the Distri- 

 bution of the Crayfishes," * that the family Astacida?, as defined above, 

 naturally falls into two subordinate groups, to which I would assign tlie 

 value of subfamilies, viz.: — 



1. The PoTAMOBiiNiE, comprising the crayfishes of North America, 

 Europe, and Asia. In these the first abdominal somite in the male bears a 

 pair of styliform appendages;! the podobranchias borne on the second and 

 third maxillipeds and on the first three pairs of legs are furnished witli a 

 broad bilobed plaited lamina; the epipodite of the first maxilliped is desti- 

 tute of branchial filaments; the coxopoditic set03 are acute, not hooked, at 

 the end ; the telson is commonly divided more or less completely by a 

 transverse suture. 



The subfamily Potaniobiinaa includes two genera : — 



«. Camhanis, distinguished principally by the absence of gills on the last 

 thoracic somite and the absence of a bilobed lamina from tlie podobranchia) 

 of the penultimate pair of legs. (Page 3.) 



h. As/aciis, characterized chiefly by the presence of a pair of branchiae 

 on the wall of the last thoracic somite, and a folded lamina on the podo- 

 branchia? of the thoracic appendages from the second maxilliped to the 

 jjenultimate pair of legs inclusive. (Page 125.) 



2. The PARASTACijSTiE, comprising all the crayfishes of the Southern 

 hemisphere ; viz. those of South America, Madagascar, Australia, Tasma- 

 nia, New Zealand, and the Feejee Islands. t In this subfamily the first 

 abdominal somite is devoid of appendages in both sexes ; the podobranchia) 



* Proc. Zoolog. Roc. London, 1878, pp. 752-788. 



f The iirst. abdominal appendages are rudimentary or absent in the female. 



J 111 the collcetiim of the United States National Mnseum there is a specimen of an undescribcd Pa- 

 rastacine from Colima, Mexico, collected by J. Xaiitns. Tliis is the only repi-osentative of the Paraslacinse 

 which has been found north of the equator. Aceording to Ilnxley, op. cit., p. 771, there arc two specimens 

 of Paranephrops from the Teejee Islands in the British Museum. Perhaps the locality labels of the Mexican 

 and Feejee specimens arc erroneous. 



