14 OPHIOMASTIX JAXUALIS. 



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

 no little peak in the under arm-plate next the tentacle-scale. Perhaps 

 another species, perhaps only a variety. 



0. sinensia looks a good deal like 0. lacertosa of Europe, but is distin- 

 guished by wanting the additional comb of papillce on the base of the 

 arm, and in having fewer tentacle-scales. 



Ophiomastix janualis. Sp. nov. 



Plate L, figs. 13, 14. 



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

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

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

 the uppermost longest. 



Diameter of disk, 5.5 mm ' ; arm nearly cylindrical, 1.2 mm ' wide ; very 

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

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

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

 papilla 1 , to that between outer corners of mouth-slits, 1.2 : 1.5. Tooth- 

 papilla) four, arranged in a close clump, directly below the teeth, which 

 are as in Ophiocoma. Mouth-papillae, 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, 

 narrower within than without, angles rounded ; length to breadth, 

 .9 : .0. Side mouth-shields triangular, lying along the sides of the 

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

 out than within, with a little peak without, and their sides a little 

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

 out, the plates become more elongated, with a clean curve without, 

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

 jecting but slightly ; at base of arm they meet neither above nor 

 below, but, at the 11th upper arm-plate, they meet above. Upper arm- 

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

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

 in the interbrachial spaces below, each about \ mm ~ 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 

 surface are a few sharp spines, 1.5 mm ' 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-spines three, rounded, slightly tapering, blunt; 



