138 AET. 2. — H. MATSUMOTO : 



small oral region, the slender, skin-covered arms, the narrow 

 ventral arm plates, of which the outer border is slightly notched, 

 the short, stout, skin- covered arm spines and the conical, not 

 leaf-like tentacle scales show that it is only distantly related to 

 that genus. On the other hand, the present species is very near 

 to 0. cliaphora, which appears to me to find its natural place in 

 this germs. 



Ophiosemnofes tylota (Clark). 



OpMoJebcs tylota : Clark, Bull. U. 8. Nat. Mus., LXXV, 1911. p. 243, 

 fig. 117. 



Sea of Japan ; 90-207 fathoms (Clakk). 

 Bering Sea. 



Family 2. Hemieuryalidae (Verrill, 1899) mihi, 1915. 



Disk covered with very heavy plates and stout radial shields, 

 the primaries being usually very conspicuous. Interbrachial ventral 

 surfaces very small, with very short genital slits. Oral and adorai 

 shields very thick. Three or four flat oral papillae on either side 

 of each jaw. Teeth triangular, arranged in a single vertical 

 series. Dental papillae absent. Peristomial plates simple, stout, 

 soldered with the oral frames, which are also very stout. Genital 

 plate and scale of the same side of a radius soldered together, very 

 stout. Arms very stout, covered with very heavy arm plates, vertical- 

 ly coiled. Vertebrae stout. Vertebral articulations streptospondyline, 

 articular pegs being very rudimentary or entirely absent. 



This family includes seven genera, which may be grouped 

 into two subfamilies as follows. 



Subfamily 1. Ophioi^hondrince (Verrill, 1899) mihi, 1915. — 



