126 A ItEVISIOX OF THE ASTACID.^. 



appendages of the male are neither bifid nor toothed at the tip, and there 

 are no hooks near the base of any of the thoracic legs. 



The Astaci from Western Asia curiously simulate the Cambari of North 

 America in the general shape of the subcylindrical body and in the form 

 of the chelipeds. The second and third j^airs of thoracic legs of the male 

 bear hooks on the third segment similar to those of the male Cambarus, 

 and the first pair of abdominal appendages are terminated with short teeth. 

 The three Asiatic species, A. Japonicns, Dauricus, and Schrenckii, thus form 

 a second natural group, combining some of the characters of Astacus and 

 Cambarus. This group I have called Cambaroides. 



Subgenus CAMBAROIDES. 



Cephalothorax subcylindrical. Last thoracic segment bearing a pair of 

 pleurobranchiiB. Third segment of second and third pairs of legs of the 

 male hooked. First pair of abdominal appendages of the male terminating 

 in short teeth or tubercles. 



The three species Astacus Japonicns, Dmiriciis, and Schrenckii, from Japan 

 and the basin of the Amoor Eiver, widely separated from the rest of their 

 family in geographical position, form a natural, group of subgeneric value, 

 to which I have given the name Cambaroides. In them is found a com- 

 bination of characters of Astacus and Cambarus. In the general appear- 

 ance of the body, with its subcylindrical cephalothorax, and in the form 

 of the rostrum and chelipeds, these Asiatic Astacidte strikingly i-ecall the 

 Cambari of North America, and their affinity is made more evident through 

 the hooked thoracic legs and tooth-tipped sexual appendages of the male. 

 The hooks are situate, in all these species, on the third segment of the 

 second and third pairs of legs, as in Cambarus Monicsimia^ and Shtfeldtii. 

 The rostrum is devoid of lateral teeth. The carpus is armed with a strong 

 median internal and an anterior inferior spine. The external flagellum of 

 the antennules is serrate below, each segment being produced at its antero- 

 inferior angle, which bears a bundle of eight or ten of Lej'dig's olfactory 

 organs. These are arranged in a single group on each antennulary segment, 

 instead of being distributed into two bundles, as in Cambarus and Astacus 

 proper.* The front border of the carapace is strongly angulated behind the 



* Tlie same arrangement of the olfactory seise is foiiiid iu tlic Parastacinse. 



