A. JEJ. Verrill — North American Ophinroidea. 357 



The radial shields are large, elongated, separated by a band of small 

 flat scales. Central part of disk and interradial spaces covered by- 

 very small, flat, naked scales. The arms ai"e relatively stout, of 

 moderate length, tapering rapidly. 



O. convolutxis L, is described as having the disk granulated ; oral 

 papillae four and squarish ; oral shield broader ; radial shields shorter 

 and broader ; besides other differences. Possibly the two forms 

 may be only variations of one species, but none of my specimens are 

 intermediate. 



One of the specimens from Station 232 was clinging closely to a 

 group of Zoanthoid corals {Epizoantlixis). The genus is evidently 

 adapted to living clinging to gorgonians and similar organisms, for 

 protection. 



Family, OPHIOSCOLICID Ltk., 1869. 



Ophiomyxidce (pars) Ljung., 1866. 

 Ophioscolicince (sub-family) Ljung., 1871. 



The upper side of the arms is covered with naked skin, beneath 

 which the arm-bones can usually be seen. Under arm-plates and 

 side arm-plates are present, though sometimes much degenerated. 

 Arm-spines are moderately long, often rough or thorny, two to six 

 in number. Tentacle-scale often wanting, but three or four are 

 present in Ophiambix. Oral papillae are usually numerous and form 

 a continuous row, but sometimes they are few, and rarely lacking (in 

 Ophiobyrsa). Tooth-papillae usually lacking, rarely present as irreg- 

 ular spiniform papillae. Teeth simple, spiniform. 



Disk covered with a soft skin, which may contain minute scales 

 and may bear granules or spinules. Radial shields small or rudi- 

 mentary, sometimes lacking. Oral and adoral shields normal. 



Internally the arm-bones of Ophioscolex are deeply grooved ven- 

 trally and dorsally and cut away laterally at the ends ; the mouth- 

 frames are reduced and simple, but the pei'istomial plates are large 

 and in three pieces. 



In some of the other genera the arm-bones are more rudimentary. 

 In Ophiogeron and Ophiosciasma they are entirely separated, 

 along the median plane, in two elongated parts, curved towards each 

 other. This is an embryonic character, illustrating the relatively 

 low development of the skeleton in this family. 



This family, as now known, seems to be more nearly allied to 

 Ophiacanthidoe than to OpJiiomyxidve, with which it was formerly 

 united. 



