MUSEUM OF COMPARATIVE ZOOLOGY. 137 



Ophiacantha tuberculosa sp. nov. 



Plate A'lII. Figs. 204, Z05. 



Special Marks. — Disk wrinkled and beset with coarse grains ; four smootli 

 stout arm-spines. 



Description of a?i Individual (Station 210). — Diameter of disk 6.5 mm. 

 Length of arm 32 mm. Width of arm without spines 2 mm. Seven stout 

 blunt mouth-papilla;, whereof the innermost is spearhead-shaped and stands 

 under the teeth, which are four in ni;mber, flat and square, with rounded cor- 

 ners. Mouth-shields small, much wider than long, with an obtuse angle within 

 and a little peak without ; length to breadth .8 : 1. Side mouth-shields short, 

 nearly crescent-shape, with the curve outward ; scarcely meeting within. Un- 

 der arm-plates thick and distinct, four-sided, somewhat broader than long, 

 with outer side curved and the others nearly straight, except second plate, 

 which is nearly pentagonal, with a very obtuse angle within. Side arm-plates 

 slightly projecting, meeting narrowly below and not at all above. Upper 

 arm-plates thick and well marked, four-sided, with outer corners rounded, 

 much wider without than within. Disk contracted in interbrachial spaces, 

 with deep radiating furrows between the narrow radial shields, which are com- 

 Iiletely hidden, as well as the disk-scales, by the skin and by numerous small 

 conical tubercles, which are larger and closer set on the radial shields. Four 

 stout, blunt, cylindrical, smooth arm-spines ; upper one much largest ; lengths 

 to that of an arm-joint 2, 1.4, 1, 1 : 1. One rather small tentacle-scale, longer 

 than wide, pointed, and not encroaching (as is usual in the genus) on the un- 

 der arm-plate. Color in alcohol, very pale brown. 



This species is one of the most aberrant in the genus ; the arm-spines, 

 smooth and only four in number, and the minute disk-tubercles, instead of 

 thorny grains, remind one rather of Ophiocoma. Indeed, OpJiiacaiitha bidentnta 

 and 0. vivipara, which somewhat resemble this species, have been described 

 under Ophiocoma ; but the general structure is that of a true Ophiacantha. 



Station 210, 375 fathoms, 1 specimen. 



Ophiacantha vepratica sp. nov. 



* Plate X. Figs. 245-247. 



Special Marks. — Disk closely beset with grains, among which are a few short 

 spines. Seven not thorny, translucent, slender arm -spines. 



Description of an Individual (Station 171). — Diameter of disk 6.5 mm. 

 Length of arm about 30 mm. Width of arm without spines 1.8 mm. Mouth- 

 papillfB stout, conical, blunt, three on each side of an angle, and a larger odd 

 one at the apex within, which is similar to the five teeth standing immediately 

 above it. Mouth-shields small, about as long as broad, bounded within by an 

 obtuse angle, and without by a deep curve or truncated angle ; length to 



