66 JOURNAL OF ENTOMOLOGY AND ZOOLOGY 



notably bare, while In hexacanthus it is indistinguishable. Seen from 

 above, the smooth, nearly pentagonal disk of hexacanthus with bare 

 radial shields, is markedly different from the somewhat swollen disk 

 of macidosiis, bulging a little in each interradius, covered with more 

 or less lumpy plates and with concealed radial shields. In hexa- 

 canthus the arms are more than twice the diameter of the disk, while 

 in macidosus they are only once and a half the disk diameter. It is 

 to be hoped that further material of both species will soon be se- 

 cured to throw light on the habits as well as on the morphology. It 

 is particularly important to learn to what extent the granulation of 

 disk and arms is variable. If individual diversity in this feature is 

 very great, a good series of specimens may demonstrate that 

 Ophioncus and Ophiocryptus are identical. 



