348 A. M Verrill — North American Ophmroidea. 



0. lineolata (Lym.). Disk and radial shields closely covered with 

 granules and spines. Jaws bear granules. Arm-spines seven. 



aa. — Dorsal arm-plates separate. Rows of spines not closely 

 approximate. Two or three tooth-papillae. Spines nearly 

 smooth or finely serrulate or thorny; some a little flattened. 



0. sertata (Lym.). Arm-spines seven. Tentacle-scale large, flat. 

 Two flat, distal, oral scales. Disk covered with granules and 

 tapered spines. Radial shields sometimes naked, ovate, separate, 

 but usually concealed. 



0. Valenciennesi (Lym.). Tooth -paj)il]ae three; oral tentacle-pore 

 large, marginal, with a large round distal scale ; a pair of small 

 papillae on first under arm-plate ; two large tentacle-scales. Spines 

 four, with blunt thorny tips. Disk granulated. 



To this group may also be referred 0. placentigera (Lym.), off 

 Fiji Is., 3 350 fath. It has three tooth-papilla^ ; a large, broad, oral 

 tentacle-scale ; granulated disk ; six smooth spines ; one tentacle- 

 scale. 



Amphipsila Veriill, 1899o, p. 55. Type, A. inac\ilata Ver. 

 Plate XLIII. Figures 5, 5a. 



Disk rounded, covered with thin, naked scales, above and below. 

 Radial shields narrow, separated, naked. Arm-plates distinct, above 

 and below. Arm-spines of moderate length, numerous (five to 

 twelve), serrulate. Oral shields clearly visible, at least when dry. 

 A simple row of oral papilla. Only two or three conical apical 

 papillae, in a row ; these may be considered as tooth-papillse, but 

 there is no distinct cluster of inner tooth-papillae, below the teeth, as 

 in Ophiopsila. Tentacle-scale spiniform. 



I have separated this genus from Ophiopsila, as understood by 

 Lyman, for he included in the latter A. fulva (Lym.), which is 

 closely allied to our type-species. 



In true Oiyhiopsila (type, O. aranea), to which 0. Hiisei of the 

 West Indies also belongs, there is a cluster of many special tooth- 

 papillae, within the mouth, below the teeth, as in Ophiocoma, and 

 the disk is covered with thick cuticle, nearly or quite concealing the 

 scales. It appears to belong to the family Ophiocomidce, while our 

 genus seems to be closely related to Ophiacantha, with which it 

 agrees in its mouth-parts and spines. It differs from typical Ophia- 

 cantha it its naked disk-scales and radial shields, in having the upper 

 arm-plates joined, and in the distal prolongation of the adoral plates, 

 much as in Ophiopristis and Ophiolimna, though less distinct, ow- 

 ing to its narrowness. 



