CRUSTACEA. 401 



in some there are no teeth at all, either on the carapace or the 

 rostrum ; in others, a few small inconspicuous serrations, and 

 in others a few small teeth. It is readily distinguished from 

 H. polaris, and from all other species, by the characters given 

 above. 



HIPPOLYTE ACULEATA (Fabr.). 



Thorace gibboso, fortiter quinque-dentato, rostro tenui, pedunculo an- 

 tennae superioris vix longiore. 



Cancer aculeatus, Oth. Fabr., Fauna Grcenl., No. 217. 



Alplmus aculeatus, Sab., App. to Parry's Voyage, p. ccxxxvii. t. ii. 



f. 9, 10. 

 Hippolyte aculeata, Edw., Hist. Nat. ii. p. 380. 



A single small specimen only was found in the collection, 

 without any distinct locality being named. Colonel Sabine 

 states that several specimens were found at Melville Island. 

 It is at once recognized by the slender short rostrum and the 

 extraordinary gibbosity of the carapace. 



HIPPOLYTE POLARIS (Sabine). 



Thorace gibboso, antice carinato, rostro lamella antennae snperioris 



breviore, chelis et nnguibus apice nigris. 

 Alphosm polaris, Sabine, App. to Parry's Voyage, p. ccxxxviii. t. ii. 



f. 5-8. 

 Hippolyte polaris, Edw., Hist. Nat. des Crust, ii. p. 376 ; Owen, 



in Ross's Voy., p. Ixxxv. 



In this species the female is so much larger than the male, 

 and the thorax so much more strongly gibbous, that the two 

 sexes might at first sight be readily mistaken for different 

 species. The figure given by Colonel Sabine is that of a male. 



The number of teeth on the rostrum varies greatly ; I found 

 from two to four on the upper, and from two to five on the 

 under side. Colonel Sabine states from three to six above and 

 from two to six below. Milne Edwards has erroneously given 

 eight to ten on the upper, and two or three on the under side. 

 The carapace has invariably three teeth on the carina. 



It would appear to be an abundant species, as there were 



