MOXOGRArH OF JAPANESE OPHIUROIDEA. 145 



conspicuous articular pit near the outer end for the reception of a 

 large, ball-like articular condyle of the genital plate, which is 

 entirely free from the ]3asal vertebr99. Genital scales short, wide, 

 flat, leaf-like. Peristomial plates entire, very large. Oral frames 

 not very stout, without well developed lateral wings. Oral plates 

 long and slender in interior view. Dental plates very small, or 

 absent. Teeth and oral papillsG present ; but no dental papilla?. 

 Arms slender, inserted ventrally to the disk, being only horizontally 

 flexible. Dorsal, lateral and ventral arm plates all well developed. 

 Three to five arm spines, conical or cylindrical, with smooth 

 surface. One or two tentacle scales. Vertebra} slender, with 

 zygospondyline articulation ; in the distal part of the arms, they 

 are often incompletely divided into halves by a longitudinal series 

 of pores. 



This family includes three genera, which may be grouped as 

 follows. 



I. Second oral tentacle pores opening more or less outside 

 the oral slits, so that the latter are gaping. 

 Amphilepis Ljungman, 1866. 

 II. Second oral tentacle pores opening entirely within the 

 oral slits, so that the latter are closed by the oral 

 papillae. 



Amphiactis Matsumoto, 1915. 

 Ophiochytra Lyäian, 1880. 

 Though the present family much resembles the next family, 

 Amphîurldœ, in external features, the internal structures are rather 

 Lœmophiuridan, with large peristomial plates and entire oral frames. 

 The articulation of the radial shield and genital plate, as well as 

 the flat, thin genital scales, however, gives ground for placing tliis 

 family in the present order. In short, the present family is the 



