48 PROCEEDINGS OF THE ACADEMY OF [Feb., 



porite. Adoral shields long and narrow, but with widened outer 

 ends, meeting each other within. Four or five oral papillae on 

 either side, triangular, with acute apices. Teeth stout, triangular, 

 acute. 



Six arms, of which three are longer than the other three, as an 

 indication of schizogony. Dorsal arm plates entirely absent; dorsal 

 side of vertebrae clearly visible. Lateral arm plates low, meeting 

 below. First ventral arm plates very small, rhomboidal, longer 

 than wide; the following heptagonal, with strongly concave proximo- 

 lateral and outer sides (the former adjoining the tentacle pores), 

 much longer than wide, widest opposite the outer ends of the tentacle 

 pores; calcification very feeble along median line, the plates appear- 

 ing as if longitudinally grooved. In the outer half of the arm, the 

 vertebrse are more or less divided into halves by fusiform pores. 

 Two or three hyaline arm spines, converted into compound hooks, 

 with four or five denticles along the abradial side; the lowest one is 

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

 long as the corresponding arm joint. The uppermost spines of 

 either side of successive arm joints are connected by a hyaline, 

 web-like membrane, except on the basal and most distal joints. 

 Tentacle pores large, without any scale. Color in alcohol: disk 

 deep chocolate-brown, except the granules, which are white; arms 

 brownish yellow. 



Two specimens; Sagami Sea; 300 fathoms. 



This new species evidently reproduces by schizogony, as indicated 

 by the hetaractiny and the occurrence of six madreporites. 



OPHIOHYALUS gen. nov. 



Disk covered by a skin, with marginal scales. Radial shields 

 very rudimentary, forming a continuous row with the marginal 

 disk scales. Teeth and oral papillae flattened and serrate, like 

 those of Ophiomyxa, Ophiodera and Ophiohymen. Dorsal arm plates 

 present, but rudimentary, entire, thin, hyaline, separated from each 

 other by naked spaces. Vertebrae more or less divided into halves. 

 Arm spines few, converted into compound hooks. Tentacle scales 

 absent. 



This new genus is near Ophiomyxa, but differs from it in the rudi- 

 mentary radial shields, the divided vertebrae, the entire rudimentary 

 dorsal arm plates and the conversion of the arm spines into com- 

 pound hooks. In almost all characters, Ophiohyalus is more embry- 

 onal than Ophiomyxa. 



