A. jEJ. Verrill — North American Ophiuroidea. 339 



0. hirsuta. Two to four papilla in a row. 



0. ensifera. Four to five papilloe in a curved irregular row. 



* 0. S2)ectahilis. Three or four in an irregular group. 



aa. — One or two special distal oral scales or papillre, usually 

 attached to the adoral plate ; oral tentacle-j^ore large. 



O. JBartletti. One, spiniform, distal oral papilla. 



0. lineolata. Two flat papillae. 



0. sertata. Two flat papillse. 



0. Imvipellis. One flat papilla, attached to first arm-plate. 



IX. 



A pair of small, apparently movable, oral papillae attached to the 

 proximal end of the first under arm-plate, which is emarginate.f In 

 most species of the genus there are, in this place, two flat, usually 

 fixed, processes or crests. It is generally impossible to tell, from 

 published figures, the character of these parts. They are generally 

 badly represented. 



* 0. anomala. 



0. Immpellis. (See group VIII, ««.) 



X. 



Oral papillje unusually large and stout. 



* 0. crassidens. Thx-ee or four thick and rough papillae, the distal 

 ones smaller. 



* 0. varispina. Three or four broad, flat, obtuse papillae. 



XI. 



Tentacle-scales of peculiar or unusual forms, or spiniform, 



a. — Tentacle-scales elongated ; flat, spatulate, or lobate distally. 



0. aspera. End of tentacle-scale branched or thorny. 



* 0. varispina. End spatulate. 



aa. — Tentacle-scales elongated, slender or spiniform. 



0. ec.hinxdata. Scales dagger-shaped ; two pairs on first joint. 

 0. cervicornis. Two, spiniform, slender. 

 0. Troscheli. One, long, acute. 



f Of extralimital species, O. serrata Lym., O. cornuta Lym., and 0. Valen- 

 ciennesi Lym. belong to this group. 



