V2 ART. 2. — H. MATSUMOTO : 



Family 1. Ophiacanthidse (Pekkiee, 1891) mihi, 1915. 



Disk covered by a soft skin or witli fine scales, and usually 

 beset with granules, spines or stumpy tubercles. The radial shield 

 and genital plate articulate with each other by means of a trans- 

 verse ridge or a simple face on both the plates. The genital plate 

 and scale on either side of each radius articulate with each other, 

 and are not soldered together. Peristomial plates entire, or rarely 

 triple, very large. Oral frames entire, without well developed 

 lateral wings. Teeth and oral papillae always present, spiniform 

 as a rule. Dental papillae rarely present, similar to the oral 

 papillae. Arms usually knotted, the spine ridges of the lateral 

 arm plates being very prominent ; inserted vei-y often laterally, 

 but sometimes ventrally, to the disk. Dorsal and ventral arm 

 plates very small, while the lateral arm plates are very well 

 developed, covering most parts of the arms. Numerous arm spines, 

 variable in number in successive arm joints, long, flagellate, 

 often hyaline and serrate. A^ertebrae slender, often incompletely 

 di\ided into halves by a series of pores. Vertebral articulation 

 zygospondyline or streptospondyline. Upper and lower nmscular 

 fossae equally large. 



This family includes thirty-three genera, which may be 

 artificially grouped as follows : 



A. Tentacle pores very large and open. 



I. Disk extraordinarily bulged up, covered by a naked 

 skin or with fine scales ; radial shields absent. 

 Ophiotholia Lyman, 1880. 

 Ophiomyces Lyman, 1869. 

 II. Disk not very high, covered by a naked skin or mere- 

 ly with fine scales ; radial shields small or rudimentary. 



