16 ART. 2. — H. MATSUMOTO : 



ends of the tentacle pores ; the calcification is very feeble along 

 the median line, so that the plates appear as if grooved. Two or 

 three arm spines, transparent, except the ball-like base, which is 

 opaque ; all converted into compound hooks, with four or five 

 denticles along the abradial side ; the lowest spine is slightly- 

 shorter than the upper ones, which are about two-thirds as long 

 as the corresponding arm joint, except in the very basal arm 

 joints, where they are shorter. The uppermost spines of either 

 side of successive arm joints are connected together by a hyaline 

 membrane, except in the very basal and very distal parts of the 

 arm. Tentacle pores large, without any scales. 



Colour in alcohol : disk deep chocolate brown, except the cal- 

 careous granules, which are white ; arms brownish yellow. 



This species evidently reproduce by scliizogony, as in- 

 dicated by the heteractiny and by the occurrence of six madre- 

 porites. 



Ophiohyalus Matsumoto, 1915. 



Disk covered by a soft skin, with a row of marginal scales. 

 Radial shields very rudimentary, insignificant, forming a continuous 

 row with the marginal scales. Oral papillao and teeth present, 

 flattened and serrate along the free edge. Dental papillae absent. 

 Arms very slender, only horizontally flexible. Vertebra3 more or 

 less, or entirely, divided into halves by a longitudinal fusiform 

 pore. Dorsal arm plates present, entire, but very rudimentary, 

 transparent, separated from each other by a naked space. Two 

 or three arm spines, all converted into compound hooks. Tentacle 

 scales absent. 



This genus is very near to Ophiomyxa, but difiers from it 

 in the very rudimentary radial shields, in the more markedly 



