264 CALMAN. 



The larger of the two specimens in the Columbia University 

 collection agrees with Stimpson's figures and description of the 

 type species, save that the marginal serrations are almost obso- 

 lete. The second very small specimen, however, is strikingly 

 different in general appearance. The carapace is approximately 

 triangular, the posterolateral margins being nearly in a straight 

 line, while the orbital notches are shallower, and the truncated 

 rostrum more prominent than in any other specimens we have 

 seen. A comparison of these and other specimens in the Mu- 

 seum of University College suggests the probability that some 

 at least of the described species of this genus are based on 

 characters varying with the age of the individual. 



HlPPOLYTID.^. 



The generic name Hippolyte has been used in its older and 

 wider signification, since Spence Bate's subdivision of the genus 

 (Challenger Rep. Macrura, p. 576) does not appear to be satis- 

 factory. 



Hippolyte prionota Stimpson. 



H. /;76';/d?/<2 Stimpson, Proc. Acad. Nat. Sci. Philad., 1864. 153. 

 H. prionota Kingsley, Bull. Essex Inst. XIV, (1882), 127, 

 PL ii, f. 9. 1883. 



Kingsley's figure of this species shows the serrated dorsal 

 crest passing in an even curve into the rostrum. In our speci- 

 mens a slight depression separates the crest from the rostrum, 

 and the latter is more truncate at the tip. Kingsley's figure 

 omits the three orbital spines which are characteristic of the 

 species. 



Hyppolyte gracilis Stimpson. 



H. gracilis '^\\.vi\'^^ox\, Proc. Acad. Nat. Sci. Philad., 1864. 155. 



A single somewhat damaged specimen is probably referable 

 to this species. It differs from Stimpson's description in the 

 fact that the most anterior of the four teeth on the rostrum 



