304 AKT. 2. — H. MATSUMOTO : 



usually double or triple, of moderate length or sometimes very long. 

 The genital plate and scale of the same side of a radius articulate 

 with each other near the outer end, both being very long and 

 narrow. Arms very long and slender, inserted ventrally to the 

 disk. Arm plates all well developed, or sometimes the dorsal 

 and ventral ones may be very rudimentary. Two, or sometimes 

 more, arm spines, short, conical, lying flat on the arm. One or 

 two tentacle scales to each pore, which is sometimes very large. 



This family includes seven genera, which may be grouped as 

 follows. 



I. Single tentacle scale ; dorsal arm plates well developed, 

 widely in contact with one another. 

 Ophiopcepale Ljungman, 1871. 

 OpMocirce Kœhlee, 1904. 

 Ophioleuce Kœhlee, 1904. 

 OphîopaUas Kœhlee, 1904. 

 IL Single tentacle scale ; dorsal arm plates very rudimentary, 

 extremely minute. 



Ophiotrochus Lyman, 1878. 

 III. Two tentacle scales ; dorsal arm plates well developed, 

 widely in contact with one another. 

 OpJiiernus Lyman, 1878. 

 Ophiopyren Lyivlin, 1878. 

 In Ophioleuce charischema (Claek), the peristomial plates are 

 moderately large, triple, the paired ones being usually separated 

 from each other by a median one. The oral plates are long and 

 very slender. The oral fi-ames are also long and slender, without 

 lateral wings. The basal vertebra^ are relatively very long, the 

 first one being the shortest and more or less discoidal. The 

 genital plates are long and bar-like, with two articular condyles 



