MONOGEAPH OF JAP.\NESE OPHIUEOIDEA. 25 



some fine scales in the former. Radial shields very rudimentary 

 (apparently " absent "), lying marginally. Oral sKts small. Single 

 oral papiUa on either side, and two or three dental papilla) at the 

 apex of each jaw. Teeth in a single vertical row. Teeth and 

 papillœ all alike, stout, stumpy, conspicuously thorny at tip. 

 Second oral tentacle pores opening outside the oral slits, each 

 provided with a thorny, stumpy papiUa, which arises from the 

 adorai shield. Arms verticaHy coiled. Vertebra very stout, with 

 saddle-shaped articulation. Dorsal arm plates entirely absent, 

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

 of the arms is covered merely by a naked skin. Two or three 

 arm spines, all converted into compound hooks. Tentacle scales 

 absent. 



This genus rather resembles OpUophrixus in the total 

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

 rudimentary radial shields, in the peculiarities of the teeth and 

 papilla?, and in the conversion of all the arm spines into compound 

 hooks. This last character is also found in Ophiobrachlon, but the 

 present genus differs from it in the total absence of the disk spines, 

 in the peculiarities of the teeth and papilla?, and in the fewer arm 

 spines. 



Oj>7iiosmilax inirahilis Matsumoto. 



OpUosmilax inirahilis : Matsümoto, Proc. Acad. Nat. Sei. Philadelphia, 

 LXYn, 1915, p. 50. 



One specimen ; Mora- out- Oisegaké, Sagami Sea ; 300 fathoms. 

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

 arms at base 0.8 mm. 



Disk flat, pentagonal, with concave interbracliial borders, 

 covered by a thick skin, which contains very fine, tliin, trans- 



