RECENT OPHIURANS. 215 



nates Ophiacantha hirsuta (p. 44) as the type-species. I am not satisfied that 

 hirsuta is generically different from Ophiacantha but cervicornis certainly is, and I 

 do not think these two species should be placed in the same genus. I am therefore 

 obhged to relegate Ophiopristis, for the present at least, to the hst of synonyms 

 of Ophiacantha, while cervicornis has to become the type of a new genus, char- 

 acterized by concealed radial shields, large tentacle-pores guarded by two or 

 more tentacle-scales (at least on basal arm-joints) of which one is attached to 

 the under arm-plate, and numerous oral papillae confluent with the long and 

 slender spinelets which guard the oral tentacle-pore. Of the four species 

 included in the genus only two are strictly congeneric, cervicorne and permixtum; 

 they are strikingly alike and may possibly be identical. The species here first 

 described as imperfectum may not belong in Ophioprium and the same is true of 

 the Australian species, axiologum, but for the present, while lacking adequate 

 material, a loose definition of the genus will give them a temporary resting- 

 place. 



396. O. CERVICORNE (Lyman). 



Ophiacantha cervicornis Lyman, 1883. Bull. M. C. Z., 10, p. 257, pi. 5, f. 76-78. 



HoLOTYPE. OFF St. Vincent, 573 fms. 



397. 0. IMPERFECTUM, sp. nov. Plate 3, f. 7, 8. 



Disk missing; approximately 5 mm. in diameter; arms 20-25 mm. long. 

 Upper arms-plates triangular, the base (distal margin) broadly curved, about 

 as wide as long, separated from each other. Oral shields large, triangular, wider 

 than long; distal margin nearly straight. Adoral plates not distinguishable, 

 but necessarily very narrow. Oral papillae small, pointed, 3 or 4 on each side, 

 the series confluent with 3 or 4 distinctly larger and flatter papillae protecting 

 the oral tentacle-pore. Under arm-plates long and narrow, the ends convexly 

 curved, the sides markedly concave, separated from each other. Side arm-plates 

 not prominent but meeting both above and below; each plate carries 4 or 5 

 flattened, pointed, smooth, opaque but hollow spines, the uppermost somewhat 

 the longest but the others not markedly shorter. Tentacle-scales, 3 (on basal 

 joints), narrow and pointed; one of them is attached to the under arm-plate. 

 Color, dirty whitish. 



HoLOTYPE (M. C. Z. 2167). off St. Vincent, 424 fms. Blake Station 

 226. 



This specimen is labeled by Mr. Lyman: " Ophioscolex? Ophiolebes? 2-3 

 spiniform tentacle scales. Thin upper arm plates. Soft disk-skin. 4 flat. 



