A. M Verrill — N'orth American Ophivroidea. 347 



Ophiopristis Ver., 1899o, pp. 39, 44, 47. Type, O. hirsuta (Lym.) Ver. 



Adoral plates elongated, tbree-lobed; the distal end is two-lobed; 

 one distal lobe joins the first under arm-plate ; the other joins the 

 first side arm-plate and separates it from the oral shields, so that the 

 oral shield is quite detached from the side arm-plates, as in Ophio- 

 copa. Disk-scales bear spinules or granules. Radial shields are 

 separated, mostly concealed by cuticle. Arm-spines rather long; in 

 the typical group, mostly flattened and with regularly serrulate 

 edges. The rows are not approximate dorsally. Tentacle-scales 

 one or two. 



Tooth-papillae two to four. Oral papillae numerous ; two or more 

 of these are special oral tentacle-papillae or scales, guarding the 

 large oiiter oral tentacle-pore, which is on or near the margin of the 

 jaw and is conspicuous. First under arm-plate is concave and has 

 a flat process on each inner corner. 



Synoptical table of Ophiopristis and Ophiotreta. 



A. — Typical Ophiopristis. A row of several small conical or slen- 

 der, distal, oral tentacle-papillae outside the large pore. 

 Arm-spines partly flat with serrulate edges. Two or three 

 tooth-papillae. Dorsal arm-plates separated, but rows of 

 spines not approximate. 



O. hirsuta Lym. (See p. 336.) 



O. ensifera Ver. (See p. 336, PI. xliii, fig. 4.) 



0. cervicornis Lym. A regular row of four or five slender oral 

 tentacle-papillae. Two tooth -papillae. Two spiniform tentacle-scales; 

 the pores very large and open. Disk and radial shields covered with 

 fine granules and small acute spinules ; some spinules on upper arm- 

 plates. Six short flat spines serrate on the edges. 



AA. — Op)hiotretaYeTY\\\, 1899o!, p. 40. (See p. 333.) Spines terete or 

 only little flattened. One or two, rarely three, distal oral 

 papillae or scales at the large oral tentacle-pore. Two to 

 five or more tooth-papillae. 



a. — Dorsal arm-plates joined. Rows of spines not appi'oximate 

 dorsally. Spines nearly smooth. Tooth-papillae three to 

 five. Distal oral tentacle-scales flat, blunt, two or three. 

 Two tentacle scales on several basal joints ; one is flat, the 

 other spiniform. 



