112 



University of California Publications in Zoology [Vol. 23 



Genus Calastacus Faxon 



Carapace subcylindrical, back arched, dorsally carinate; cervical groove dis- 

 tinct. Eyes almost or quite without pigment. Antennal "thorns" both of good 

 size. Exopodite of uropods with a suture. 



Key to the California Species of Calastacus 



I. Carapace granulate; no spines behind those at the base of rostrum. (Known 



only from 345 + fathoms.) 



investigatoris, p. 112. 



II. Carapace not granulate; five rows of spines behind the rostrum. (Known 



only from 200 + fathoms.) 



quinqueseriatus, p. 113. 



Calastacus investigatoris Anderson 



Calastacus investigatoris Anderson, Jour. Asiatic Soc. Bengal, 65, pt. 2, 

 p. 97, 1896; Illus. Zool. "Investigator," Crust., pt. 4, pi. 25, fig. 1, 

 1896; Alcock, Descr. Cat. Indian Deep Sea Crust. Dee. Macr. Anom. 

 Indian Mus., p. 191, 1901; Eathbun, H. A. E., 10, 151, 1904. 



Fig. 75. 

 Alcock) . 



Calastacus investigatoris; a, dorsal view; o, lateral view (after 



Characters. — Carapace (rostrum included), measured in the middle line, as 

 long as the first five and a half abdominal somites ; surface studded with sharpish, 

 vesiculous granules; finely carinated in the middle line, carina terminating in a 

 vesiculous tubercle and having a similar tubercle in the middle of its gastric 

 course; cervical and branchial grooves very conspicuous. Eostrum not quite 

 reaching end of second joint of antennular peduncle, its sides prolonged onto the 

 gastric region as two sharp ridges, each of which carries two spines. In the 



