150 PROCEEDINGS OF THE AMERICAN ACADEMY 



from the rest of their family in geographical position, form a natural 

 group of sub-generic value to which I have given the name 

 Cambaroides. In them is found a combination of characters of 

 Astacus and Cambarus. In the general appearance of the body, 

 with its sub-cylindrical cephalo-thorax, and in the form of the 

 rostrum and chelipeds, these Asiatic Astacines strikingly recall 

 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 3fontezum.ee and Cambarus Shufeldtii. In all the 

 male examples of Cambaroides that I have seen (one A. Dauricus, 

 three A. Japonicus) the first abdominal appendages are divided 

 into two sections by a transverse suture, and furnished with short 

 blunt teeth at the tip. I suspect the existence of two forms 

 of the male here, as in Cambarus, for in the male specimen of 

 A. Dauricus the hooks on the thoracic legs are strongly devel- 

 oped, and some of the teeth at the apex of the first abdominal 

 appendages are brown and corneous, whilst in the three male 

 A. Japonicus the hooks of the thoracic legs are weak, and the 

 terminal teeth of the first abdominal appendages are smaller and 

 not corneous. In A. Schrenckii there is a transverse tubercle 

 behind the sternum of the penultimate thoracic somite, much as in 

 Astacus proper. In A. Dauricus and A. Japonicus this trans- 

 verse tubercle is hollowed out behind, but still remains closely 

 soldered to the sternum. The first abdominal somite of the 

 female is devoid of appendages. I have examined the branchiae 

 in A. Japonicus, and find them to agree in number and arrange- 

 ment with those of A. fluviatilis, there being one pleurobranchia 

 (on each side) upon the last thoracic somite, and one simple 

 branchial filament on each of the three antecedent somites. The 

 structure of the branchiae and coxopoditic setae is the same as in 

 the true Astaci. 



Prof. C. O. Whitman, to whom the Museum of Comparative 

 Zoology is indebted for four specimens of A. Japonicus, informs 

 me that during his sojourn in Japan he could not learn of the 

 occurrence of Crayfishes in Hondo, or Niphon, the main island of 

 the empire, all the specimens known to him coming from the 

 island of Yesso. Kessler's specimens came from the same locality 

 as Whitman's, viz. Hakodadi, Yesso. In Whitman's specimens, 

 as in those described by Kessler, the hind border of the telson 



