MONOGEAPH OF JAPANESE OPHIUKOIDEA. 67 



the terminal main one. According to Dödeelein, the minute hooks 

 of the annuli of the arms of Astrothorax misakiensis Döderlein 

 have a single supplementary hooklet, besides the terminal main 

 one. The position of the madreporic shield of Astrotoma agassizi 

 Lyivian is almost the same as in Astrospartiis, and such a position 

 of the shield is hardly possible unless the supplementary plates are 

 present in the space inside the interbrachial ventral surface. 



Key to Japanese genera of Gorgonocephalinœ, 



A — Arms simple; no supplementary plates in the spaces between the 

 oral angles and the interbrachial ventral sm'faces; annulations of 

 the arms continued onto tlie dorsal side of the disk, so that the 



latter is concentrically annulated as a whole Asleroporpa. 



-4^— Arms divided from the base ; supplementary plates present in the 

 spaces between the oral angles and the interbrachial ventral sur- 

 faces; disk not concentrically annulated. 

 a — ^Arm spines present from the very base. 

 b — ^Interbrachial margins of the disk with a row of marginal scales . . 



Gorgonocephalus. 



bb — ^Marginal disk scales absent Astrodendrum. 



aa — Arm spines absent at least within the first bifurcation ; marginal 

 disk scales absent. 



c — Arm spines present within the second or third bifm*cation 



Astrocladus. 



cc — Arm spines absent at least within the fourth bifurcation . . Astroboa. 



Asteroporpa hadracantha Clark. 



Asteroporpa liadracantha : Claek, Bull. U. S. Nat. Mus., LXXV, 1911, 

 p. 280, fig. 142. 



One specimen ; Uji-sliima, Osumi ; 80-90 fathoms. One speci- 



