50 PROCEEDINGS OF THE ACADEMY OF [Feb., 



a thin, transparent skin; the lower one is much larger and longer 

 than the upper. On some basal arm joints there occurs on the 

 lateral arm plate one more spine, which is placed on the dorsal 

 margin of the plate and also bears a series of booklets on one side; it 

 is larger and longer than the other two and nearly as long as the 

 corresponding arm joint. No tentacle scale. Color in alcohol: 

 yellowish white. 



Two specimens; probably Sagami Sea. 



Subfamily 2. OPHIOBYRSIN^ nov. 



(Characters as given in key, p, 46.) 



This subfamily includes Ophiobyrsa, Ophiohyr sella, Ophiophrixus, 

 Ophiobrachion and provisionally Ophioschiza, besides a new genus, 

 Ophiosmilax. 



The Ophiobyrsinse rather approach the next two families in 

 skeletal characters. 



OPHIOSMILAX gen. nov. 



Disk and arms covered by a thick skin. Radial shields very 

 rudimentary and insignificant. Single oral papilla on either side 

 and two or three dental papillae at the apex of each jaw. Teeth in 

 a single vertical series. Teeth and papillae all alike, stout, stumpy, 

 conspicuously thorny at tips. Second oral tentacle pores open 

 outside oral slits, each provided with a thorny, stumpy papilla, 

 which arises from adoral shield. Dorsal arm plates absent, while 

 the lateral arm plates are subventral, so that the dorsal side of the 

 arms is merely covered by a naked skin. Ventral arm plates well- 

 developed, in contact with each other. Vertebrae short and very 

 stout. Vertebral articulation streptospondyline, the articular peg 

 being entirely absent. Arm spines few, converted into compound 

 hooks. No tentacle scale. 



This new genus more or less resembles Ophiophrixus in the total 

 absence of dorsal arm plates, but differs from it in the rudimentary 

 radial shields, in the peculiarities of teeth and papillae and in the 

 conversion of arm spines into compound hooks. The last character 

 reminds us of Ophiobrachion, but Ophiosmilax has no disk spines, 

 while it does have peculiai* teeth and papillae and fewer and longer 

 arm spines. 

 Ophiosmilax mirabilis sp. nov. 



Diameter of disk 2 mm. Length of arms 12 mm. Width of arms 

 0.8 mm. Disk pentagonal, with concave interbrachial borders, 

 covered by a thick skin, which contains very fine, thin, transparent 



