86 



CRABS OF FAMILY MAIID^ — RATHBUN. 



Hyastenus japouicus Miers, Proc. Zoiil. Soc. T.oikIoii, ]>. L'7, jil. i, lig. L', lS7!t; (.'bal- 



lengiT Ropt., Zoiil., xvii, ]). 5G, 1XS6. 

 Hyastenus lotn/ipea Miers, Cliallciiger Rept., Zoiil., xvii, p. 56,1886. 



This species ranges from 57° nortli latitude, off Kadiak, Alaska, to 

 32° nortli latitude, off San Diego, Cal., and in depth iVoiu 27 to G()3 

 fathoms. It exhibits wide variations from Dana's tyi)es, especially in 

 more southern latitudes, where, as a rule, the carapace is very much 

 swollen at the branchial regions, making the width much greater in pro- 

 portion to the length; the second and third joints of the anteiime are 

 much more slender; the hepatic region is furnished with a sharp spine; 

 and, lastly, the tubercles of the carapace are more numerous and some 

 of them spin(ms. These characteristics, if uniform, would be specitic, 

 but the two extremes intergrade to such an extent as to render im- 

 l)0ssible even a varietal separation. The broad form is with one ex- 

 ception contined to deep water; the typical lonf/lpcx ranges from 27 

 fathoms iu the north to 456 in the south, A^ariations exist in speci- 

 mens from the same locality ; for example : The broad forms may possess 

 a hepatic si^ine or a tubercle; the antenual joints are narrow iu some 

 individuals and wide in others. Occasional specimens of the^ narrow 

 form have a sharp hepatic spine. An examination of the branchiffi 

 of the broad and narrow forms shows that they are larger in the former. 

 Corresponding differences exist in the size of the maxillipeds, the tia- 

 bella being larger, as well as the scaphognathite of the second maxilla. 

 The endopodite of the first maxilliped, however, which is seen to be so 

 different in the two species of Chionn'vclrn^ is the same size and shape 

 in the two forms of Hyastenus longipcs. 



The width of the tyi)ical form ranges from 0.71 to 0.8 of its length; 

 of the wider form, from 0.82 to 0.9 of its length; the length being- 

 measured from between the bases of the cornua. The measurements 

 are taken of male specimens, with one exception. In the following 

 tables the stations are arranged from north to south: 



Table of mcasuremcnls. 



