154 



The vertical range of the species of Heterocarpus varies rather much, not only according 

 to the species, but often also one and the same species has been observed at various depths. 

 Heteroc. Alexandri A. M.-Edw. was obtained by the "Blake" off Martinique at 1030 fathoms 

 like also Heteroc. tricarinatus Alcock & Anderson south of Muna Island : this is the greatest 

 depth, at which a species of this genus was observed. Heteroc. ensifer A. M.-Edw. on the contrary 

 occurs at less considerable depths and was taken e. g. in Pailolo Channel, Hawaiian Islands, 

 in 31 to 290 fathoms. While some species were captured at moderate depths, like Heteroc. 

 ensifer, JVood-masoni, vicariits or signatus, other ones occur in much deeper water, so e. g 

 Heteroc. Alexandri, /wslilis, Grimaldii and longirostris. 



Key to the Indopacific species of the genus Heterocarpus A. M.-Edw. 



«, Abdominal terga, though some may be bluntly carinated, 

 never produced posteriorly into overhanging spines. 

 b x Postocular carina completely wanting. Third abdominal 

 tergum armed with an acute spine, arising from the 



anterior half. Wood-mdsoni Alcock 



ó 2 Postocular carina present. No spine on third abdominal 

 tergum. 

 c l Postantennal carina completely wanting. 



Of the upper teeth of the rostrum four on the carapace, 

 the i st a little before the middle of it, the 5 th just 

 beyond the orbital margin. Dactyli of the three posterior 



legs long and slender , . . Alexandri A. M.-Edw. 



(A. Milne-Edwards, Recueil de Figures de Crustacés nouveaux ou 

 peu connus, Avril 1883, PI. 28.) 



c 2 Postantennal carina more or less developed. 

 d x Branchiostegal spine long, reaching beyond the 2 nd 

 joint of the antennal peduncle and usually projecting 

 beyond the orbital spine. 

 e 1 Postantennal carina measuring only one-fourth the length 



of the carapace unicarinafns Borr. l ) 



(L. A. Borradaile, Annals Mag. Nat. Hist. Ser. 8, Vol. XV, 1915, 

 p. 208.) 



e 2 Postantennal carina measuring at least two-thirds the 



length of the carapace. 

 /j Scaphocerite little more than half the length of the 

 carapace. 

 Dactyli of the three posterior legs of a stout shape 

 and short, those of the 3 rd pair measuring about 

 one-sixth the length of the propodi laevigatus Bate 



1) This species is placed here, because it is described as being related to Heteroc. longirostris Mac Gilchrist. 



