MONOGRAPH OP JAPANESE OPHIUROIDEA. 



69 



propose the name ophiocrcnoid for it. Judging from the presence 

 of a single madreporite and the absence of the arm spines in the 

 basal parts of the arms, Ophiocrene may probably be the ophlo- 

 crenoid stage either of Asfrohoa or of AstrocJialcis ; and if this 

 connection should be proved, Ophiocrene has priority as a generic 

 name. 



An Ophiocrenoid singe of one of the Gorgonoceplialinœ, 



Two specimens ; Mera-out-Oisegaké, Sagami Sea ; 300 fathoms. 



Diameter of disk 2.5 mm. Arms twice divided ; length of the 

 primary shafts 3 mm., of the secondary shafts 2.5 mm., and of 

 the last shafts 1.5 mm. Width of arms at base 0.7 mm. 



Disk five-lobed, rather 

 high, with strongly concave 

 interbrachial borders, cover- 

 ed by a pavement of naked 

 plates, among which the 

 central, five radiais, five 

 interradiais, as well as the 

 radial shields are most con- 

 spicuous, with convex sur- 

 faces. The secondary plates 

 arc very small and incon- 

 spicuous, and form a system 

 of zones surrounding the 

 primaries. Ventral side of 

 disk covered by a granulated 

 skin, through which the oral 

 and adorai shields can be seen as being entire and without sup- 





<£>. 



Fig. 18. An Ophiocrenoid (? Gorgonocephalus or 

 Astrodendnim). x20. a. From above, h. From 

 below. 



