22 



CARL BOVALLIUS, THE OXYCEPHALIDS. 



3. The head. 



The shape of the head of the Oxycephalids shows forms gradually 

 developing almost from the normal type in Lycceidce to the strange-look- 

 ing, extremely elongated form in Xiphocephalidae. The genus Glosso- 

 cephalus has a distinct, but thick and obtuse, tongue-shaped rostrum 

 (fig. 6 and 6 a), Oxycephalus (fig. 7 and 8), Stebbingella (fig. 3), and 

 Streetsia (fiig. 9) offer different steps of development of a more and 

 more elongated and sharp rostrum, open at the under-side; in Dory- 

 cephalus and Leptocotis (fig. 10) it has reached the form of a needle, 

 which form is so enormously developed in Xiphocephalus, that it may 

 be properly called filiform (fig. 2). 



An aberrant development of the rostral or anterior part of the 

 head occurs in Calamorhynchus where the dilation of the basal portion 

 of the rostrum, which is indicated already in Tullbergella (fig. 12), is 

 exaggerated into the large wing-like projections shown in fig. 11. 



Fig. 6. 



Fig. 6 a. Glossocephalus Milne 

 Edivardsi. 



Fi(j 7. Oxycephalus 

 Claim. <$. 



Fig. 8. Oxycephalus Cluusi. 



But also the hind part of the head shows a gradual development 

 from being in Streetsia riot constricted, in Oxycephalus, Crano- 

 cephalus, Tullbergella, and Stebbingella, feebly constricted and 

 scarcely forming a distinct neck, to Do rycephalus, Leptocotis and Cala- 

 morhynchus, where the hind part of the head is strongly constricted, 

 forming a distinct, but short neck, and lastly to Xiphocephalus, which 

 has a long and narrow neck, longer than the central part of the head (fig. 2). 



The highest part of the head, which may be situated close to the 

 anterior margin of the first peraeonal segment, as in Simorhynchotu s 



