DECAPODS 59 



H'. Rostrum concave above. Epipods on maxillipeds 



and first foot only moseri. 



G'. Maxilliped not exceeding acicle. 



H. Third abdominal segment with a lobe (in profile), 

 which is in the form of a hook in the $ , of a 

 hump in the $ . 8 to 1 2 dorsal spines 



gaimardii bekheri. 



H'. Third segment without a lobe (in profile) in the ? . 

 J. Rostrum with more than 8 spines above . layi. 

 ]'. Rostrum with 8 or fewer than 8 spines above. 

 K. Fourth abdominal segment with a spine on 



either side suckleyi. 



K'. Fourth abdominal segment without spine. 

 L. Sixth segment barely twice as long as high. 

 M. Maxillipeds reaching just beyond middle 



of acicle camtschatica. 



M'. Maxillipeds reaching nearly to end of 



acicle kincaidi. 



I/. Sixth segment more than twice as long as 



high townsendi. 



B'. Rostrum shorter than the rest of the carapace. 



C. Upper and lower limbs of rostrum deep and with convex margins. 

 D. Upper limb of rostrum deepest above the eye . . macilenta. 

 D'. Upper limb narrow above the eye . . . macrophthalma. 

 C'. Upper and lower limbs of rostrum not both convex. 



D. Rostrum elongate, reaching beyond the middle of the an- 



tennal scale. 

 E. Upper margin of rostrum concave. 



F. Fingers of first pair of chelipeds less than one third as 



long as palm. No pterygostomian spine. No spine 



on fourth segment of abdomen . . . brachydactyla. 



F'. Fingers of first pair of chelipeds about half as long as 



palm. A pterygostomian spine or spinule. A spine 



or spinule on fourth segment of abdomen maxillipcs. 



E'. Upper margin of rostrum straight. 



F. Antennal peduncle reaching end of antennular peduncle 



picta. 



F 7 . Antennal peduncle reaching end of second segment of an- 

 tennular peduncle sitchensis. 



D 1 . Rostrum short, not reaching beyond the middle of the an- 



tennal scale. 



E. Rostrum not reaching as far as the cornea . . . taylori. 

 E'. Rostrum reaching as far as or beyond the cornea. 



F. Rostrum not reaching the second segment of antennular 



peduncle. 

 G. Rostrum with superior margin strongly convex over 



the eyes, extremity straight avina. 



G'. Rostrum with superior margin not strongly convex 

 over the eyes, but nearly straight. 



