46 



Carl Bovallius, The Oxycephalids. 



A. The inner rami of the second and third pairs of 



uropoda are coalesced with the corresponding 

 peduncles. 



a 1. The first pair of perseopoda with a folding 

 hand; the second pair with a subcheliform 

 hand. The head is only a little produced, 

 and the rostrum broadly obtuse. 



a 2. The first and second pairs of perseopoda 

 with a cheliform hand. The head is pro- 

 duced into a more or less sharp-poiuted 

 rostrum. 



B. The inner ramus of the third pair of uropoda is 



coalesced with the peduncle. 

 b 1. The last ural segment is not twice as long 



as the first. 

 b 2. The last ural segment is more than twice 

 as long as the first. 

 bb 1. The anterior part of the head is dilat- 

 ed into wing-like projections. 

 bb 2. The anterior part of the head is not 

 dilated. 



\j. The inner rami of all the uropoda are free, not 

 coalesced with the peduncles. 

 C 1. The last ural segment is not twice as long 

 as the first. 

 cc 1. The hind part of the head is not 

 constricted into a neck. The head 

 is produced into a sharp rostrum. 

 The first pair of peraeopoda with a 

 subcheliform hand, the second with 

 a cheliform, the carpal process be- 

 ing more or less spine-like 

 cc 2. The hind part of the head is con- 

 stricted into a neck. 

 ccc 1. The first two pairs of perseo- 

 poda with a subcheliform 

 hand. The head is produced 

 into a sharp rostrum. 



Simorhyuchotns. 



2. Oxycephalus. 



3. Tullbergella. 



4. Calamorhynchus. 



5. Dorycephalus. 



6. Streetsia. 



