118 



CARL BOVALLIUS, THE OXYCEPHALIDS. 



1. X. armatus. 



The four species to be accounted for are distinguished as shows 

 the following synoptical table: 



A. The second pair of uropoda are shorter than the 

 last coalesced ural segment. The flagellum of 

 the first pair of antennae in the male is four- 

 jointed. The hind corner of the seventh perseon- 

 al segment is rounded. The last coalesced ural 

 segment is longer than the first. The first pair 

 of uropoda are shorter than the third. The tel- 

 son is longer than the pleon and urus together. 



D The second pair of uropoda are longer than the 

 last coalesced ural segment. The telson is shorter 

 than the pleon and urus together. 



b 1 . The last coalesced ural segment is as long 



as, or shorter than, the first. 

 bb 1. The seventh peraeonal segment is 

 not half as long as the sixth, the 

 hind corner is produced down- 

 wards into a crescent-shaped, 

 sharp-pointed process. The flag- 

 ellum of the first pair of an- 

 tennae in the male is two-jointed. 

 The first pair of uropoda are 

 about as long as the third. 

 bb 2. The seventh peraeonal segment 

 is more than hah as long as the 

 sixth, the hind corner is ob- 

 tusely angular, and only feebly 

 produced. The first pair of uro- 

 poda are much longer than 

 the third. 



b 2. The last coalesced ural segment is twice 

 as long as the first. The seventh 

 personal segment is more than half as 

 long as the sixth, the hind corner is 

 broadly rounded. The first pair of uro- 

 poda are longer than the third. 



2. X. Whitei. 



3. X. Lilljeborgi. 



4. X. brevicaudatus. 



