III. MORPHOLOGICAL SOTES OIS THE OXYCEPHAL1DS. 



/. The shape of the body. 



The genus Xiphocephalus is certainly the most extreme of all 

 the Hyperiidean forms with regard to its development in length and 

 narrowness, but this extravagant, rod-like form of body is however very 



naturally connected with the other Hype- 

 rids by intermediate links. Thus, if 

 examining the genera of the Oxycepha- 

 lids, we find first in the series the 

 thick and stout Tullbergella, (fig. 1) in 

 shape of peraeon very similar to a true 

 Hyperia, and then Oxycephalus, with 

 the body somewhat more compressed, 

 and next Stebbingella, both of them 

 with the head and the hind part of the 

 body tolerably elongated, from them is 

 an easy transition to the slender Street- 

 si a. This slender form of body is more 

 pronounced in Leptocotis and Dorycephalus, which, on the other 

 hand, are readily found to be connected with Xiphocephalus (fig. 2) 



Fig. 1. ^Tullbergella cuspidata. 



Fig. 2. Xiphocephalus armtaus. J 1 . 



by the rod-like form of body of Calamorhynchus. The body of 

 the females is usually somewhat broader than that of the males, except 

 in Xiphocephalus, where such a sexual difference is not present. 



