A. M Verrill — ISTorth American Ophiuroidea. 355 



0. vitrea Lym. Disk closely covered with small, acute spinules, 

 the scales nearly concealed. Tooth- and oral papillaB very numerous, 

 slender, acute. Nine thorny arm-spines. Tentacle-scales large, 

 obtuse. 



O. hystrix Lym. Disk-scales visible, irregulai*, bearing few, short, 

 conical, rough spinules. Radial shields in contact distally. Arm- 

 spines eight, slender, the upper ones very long. 



AA. — Dorsal arm-plates all separated. Rows of spines not approxi- 

 mate dorsally. 



O. fasciculataJjjva., ^83. Arm-spines six, rather short, flattened, 

 serrulate on the edges. Disk-scales plainly visible, bearing few 

 small, tapered, acute spinules. Radial shields not very lai-ge, broad, 

 wholly in contact. Dorsal arm-plates widely separated. 



0. austera Ver., Ophiur. Bahama Exped., p. 60, pi. vi, tigs. 1, la, 

 pi. vii, fig. 2. Arm-spines seven, slender, the upper ones very long 

 and very thorny, scarcely flattened. Disk-scales visible, bearing 

 longer and shorter, rough, acute spinules. Radial shields large, 

 triangular, extensively joined. Dorsal arm-plates nearly in contact 

 on the basal joints. Four lanceolate tentacle-scales. A cluster of 

 about six acute, distal, oral papillre, pointing inward on each side, 

 part of them arising from the lateral lobes of the deeply bilobed first 

 under arm-plate. (See this vol., Plate xliii, figure 2.) 



OPHIOCHONDRIN^, subfam. nov. 



This group differs from typical Ophiacanthidae chiefly in having 

 the internal arm-plates so modified that the arms can be coiled in a 

 vertical plane, like the Astrophytons^ etc. The arm-sj^ines are short, 

 subequal, not very rough. The disk-scales may be thickly covered 

 with cuticle and granules, or they may be naked. The oral papill?e 

 are few, in a simple row. The thick cuticle sometimes covers the 

 mouth shields and lower side of the ax'ms. 



The modifications of the ambulacral ossicles fits these species more 

 perfectly for clinging closely to gorgonians, etc, by coiling the arms 

 closely around the branches. But this power is also common to 

 various species of Ophiacantha^ in a lesser degree. 



Ophiochondrella Ver., gen. nov. Type, O. squamosus (Lym.). 



This differs from true Ophiochondrus in having the disk covered 

 with naked scales, above and below ; in having the under arm-plates 



