14 OPIIIOJMASTIX JANUALIS. 



the under side of the base of the arm, little marked or wanting, and 

 no little ])eak in the under ann-2:)late next the tentacle-scale. Perhaps 

 another species, perhaps onl}^ a variety. 



O. sinensia looks a good deal like O. lacertosa of Europe, but is distin- 

 guished by wanting the additional comb of papilla^ on the base of the 

 arm, and in having fewer tentacle-scales. 



Ophioniastix janualis. Si*, nov. 

 Plate 1., ligs. lo, 14. 



Special Maries. — Disk-scales conspicuous below, but obscured by 

 thick skin on the upper surface of disk, which is beset with sliarp 

 tapering spines ; but none below. Three round tapering arm-spines, 

 the uppci'most longest. 



Diameter of disk, 5.5"""'; arm nearly cj'lindrical, 1.2''""' wide ; very 

 slowly tapering to a length of 24;""", where it is broken off. From 

 outer corner of mouth-slit to outer side of opposite mouth-shield, 2.5""" ; 

 distance from outer side of mouth-shield to inner points of tooth- 

 papilla*, to that Ijctween outer corners of mouth-slits, 1.2 : 1.5. Tooth- 

 papillaj four, arranged in a close clump, directly below the teetli, Avhich 

 are as in Ophiocoma. Mouth-papilla?, 8, arranged in a close half-circle 

 round the mouth-angle ; outer ones flat, rounded, as long as broad ; 

 inner ones narrower and smaller. Mouth-shields longer than broad, 

 luirrower within than without, angles rounded ; length to jjreadth, 

 .9 : .0. Side mouth-shields trianfj^ular, Ivinjr alons: the sides of the 

 mouth-shields, but not meeting within. Under arm-plates wider with- 

 out than within, with a little peak Avithout, and their sides a little 

 re-enteringly curved ; length to breadth ( Hth joint), .6 : .5. Farther 

 out, the i)lates become more elongated, with a clean curve Svithout, 

 re-entering sides, and a truncated angle witiiin. Side arm-plates pro- 

 jecting l)ut slightly ; at base of arm they meet neither above nor 

 l)elow, but, at the 11th upper arm-plate, they meet above. Upper arm- 

 plates wedge-shajied, with a curved outer side, and laterals re-enter- 

 ingly curved; length to breadth (Gth plate), .7 : .6. Disk finely scaled 

 in the interbrachial spaces below, each about ^°'°'' long; above the scal- 

 ing is covered except near the edge, round the radial-shields, and at 

 the base of the arm, to which it extends. Scattered over the upper 

 surfiice are a few sharp spines, l.S™"' long, which are mounted on slight 

 elevations and stand over the places of the primary plates. The radial- 

 shields project close to the arm as little, irregular, triangular, swellings 

 about .7"'"' long. Arm-.s2)ines thi-ee, rounded, slightly tajDcring, blunt ; 



