338 A. E. Verrill — North American Ophiuroidea. 



0. sertata (three, only two visible below). 



0. Troscheli (three tooth-papillae). 



0. spectabilis (three to five tooth-papillse ; a cluster of distal oral 

 papillae. 



0. pectinula Ver. (two or three tooth papillae ; three or more 

 distal oral tentacle-papillae). 



VII. 



A pair of tooth-papillae (or apj^arent tooth-papillae) close together, 

 at the tip of the jaw ; no odd median one visible from below. (In 

 some species the odd papilla may be concealed by the j^air below it, 

 when it is actually present, but published figures and descriptions 

 are not definite enough to determine this in many cases ; in some 

 cases it may have been accidentally broken from the type-specimen. 

 It certainly seems to be the normal condition, in group a, to have 

 only two.) 



a. — A distal cluster or row of special oral tentacle-scales. See 

 Ophiopristis, p. 347. 



0. cervicoriiis. 

 0. ensifera. 

 O. hirsuta. 



aa. — Only one or two distal oral tentacle-scales. 



O. Bartletti. No tentacle-scale on arms. 



O. echinulata. Two spiniform tentacle-scales on arms. 



VIII. 



A cluster of oral papillae or oral scales near the outer corner of 

 the mouth-slits, at the outer oral tentacle-pore, or else one or two 

 special oral scales by the side of the tentacle-pore, which is on, or 

 nearly outside of, the margin of the mouth-slit. (Published figures 

 are often inaccurate as to this character,)! 



a, — Several distal oral tentacle-scales or papillae to each pore. 



0. cervicornis. About four spiniform distal papillae in a row. 

 0. 2)€Ctmtila Ver. Three to four distal papillae. 

 * 0. enopla. Four to six distal papillae in a cluster. 



f Several extralimital species belong to this group ; among them are: O. rosea 

 Lym. (in subsection a) ; O. marsupialis Lym. ; and O. Valenciennesi Lym. 

 (in aa.) 



