230 University of California Fuhlications in Zoology. [Vol. 4 



7. Propodus of first peraeopod over one-half as broad as long 8 



Propodus of first peraeopod only one-fourth as broad as long ; dactyl 



of second gnathopod with three small teeth beneath 



C. nobile Sars. 



8. Dactyl of second gnathopod with five teeth beneath; propodus of 



fifth peraeopod twice as long as the dactyl.. C. salmonis Stimpson. 

 Dactyl of second gnathopod with two teeth beneath; propodus of 



fifth peraeopod nearly four times as long as the dactyl 



C. cylindricum Say. 



9. Eamus of third uropod linear 10 



Eamus of third uropod not linear 11 



10. Dactyl of second gnathopod simple; first antennae of the male with 



a hooked process on the basal segment . C. runcicome Delia Valle. 



Dactyl of second gnathopod toothed at apex; first antennae of the 



male with the basal segment simple C. afifine Bruzelius. 



11. Carpus of fifth peraeopod almost one-half as broad as long 



C. mucronatum Sars. 



Carpus of fifth peraeopod three and one-half to four times as long 

 as broad 12 



12. Eamus of the third uropod without a terminal spine 13 



Eamus of the third uropod with a terminal spine ...C. monodon Sars. 



13. Eami of the second uropoda about normally, sub-equally, robust, 



their lateral edges bearing 3 to 5 spines and each ramus with 



three apical spines 14 



Outer ramus of second uropod stout, inner very slender; the outer 

 unarmed, except for one apical spine, the inner with one mesal 

 and two apical spines C. spinicome Stimpson. 



14. Outer edge of outer ramus of second uropod with five spines; inner 



edge of inner ramus with four spines; ultimate segment of 



peduncle of second antennae apically produced-.C. robustum Sars. 



Outer edge of outer ramus of second uropoda with three spines; 



inner edge of inner ramus with two spines; ultimate segment of 



peduncle of second antennae apically not produced 



C. curvispinum Sars. 



15. Cephalon without any rostrum C. bonelli Milne Edwards. 



Cephalon with a rostrum 16 



16. Dactyl of both first and second gnathopods simple 



C. crassicome Bruzelius. 



Dactyl of first gnathopod bifid, of second gnathopod trifid, at apex 

 C. acheruzicum A. Costa. 



Corophium spinicorne Stimpson. 



Pis. 9, figs. 1-11; 10, figs. 12-19; 13, figs. 36, 37. 

 Second antennae of the adult female (pi. 9, fig. 1) about one 

 third longer than the first (pi. 9, fig. 2). Peduncle of the first 

 pair with the basal segment stout, equal to the second, armed with 



