16 Carl Bovallius, The Oxycephalids. 



the telson and the last ural segment. The likeness between the Xip/ioce- 

 phalidœ and the Caprellids^ suggested by previous authors, is very super- 

 ficial and is no reasn for placing the Xiphocephalidœ last in the tribe*). 



C. Characteristics for the distinction of the Genera among the ' 



OXYCEPHALIDS. 



1. The general form of the head and. the. rostrum. 



2. The first pair of perœopoda being simple, — subcheliform., — or cheliform. 



3. The second pair of perœopoda being sub cheliform, — or cheliform. 



4. The inner rami of the second and third pairs of uropoda coalesced 



with the corresponding peduncles.^ — or free. 



5. The relation beticeen the length of the ural segments. 



These five characteristics are sufficient for the distinction of the 

 genera given here below as constituting the family Oxycephalidœ. 



D. Characteristics for the distinction of the Species of the 



OXYCEPHALIDEAN GENERA. 



These characteristics vary of course much in the different genera, 

 but a few which are very useful and of common occurence may be 

 pointed out here. 



1. The armature of the first tioo pairs of perœopoda. 



2. The seventh pair of perœopoda. 



3. The relation between the outer and inner rami of the tiroj^oda. 



4. The relation between the telson and the last ural segment. 



Within the genus Xiphocephalus particularly the following good 

 specific characteristics may be indicated: 



1. The form of the epimeral of the first pair of perœopoda. 



2. The form of the lateral parts of the seventh perawnal segment. 



3. The relation between the length of the first two pairs of uropoda. 



4. The relation between the last pair of uropoda and the telson. 



1) For further information on these points see my forthcoming paper »Remarks 

 on the system and synonymy of the Amphipoda Hyperiidea». 



