362 A. E. Yerrill — N'orth American Ophiuroidea. 



Ophiodera Verrill, Oph. Bahama ExpecL, p. 67, 1899. Type, O. serpentaria 

 (Lym.). 



Marginal disk-scales are rudimentarj'- and concealed by thick 

 cuticle ; the disk-scales proximal to the radial shields are lacking. 

 No upper arm-plates'. Side arm-plates may be soldered to the under 

 arm-plates. They are not continued upward b}^ a row of small 

 plates. Three or four arm-spines enclosed in cuticle; the inner one 

 is smaller and may serve as a tentacle-scale; it is sometimes forked 

 distally. Teeth and tooth-papillae serrate, neai'ly as in Ophiomyxa, 

 but with finer denticles. 



Ophiodera Stimpsoni Verrill. 



? Ophioscolex Stimjjsoni Lyman, Illust. Cat. Mus. Comp. Zool., viii, p. 23, pi. 



i, figs. 11-15, 1875. 

 Ophiodera stimpsoni Ver., Oph. Bahama Exped., p. 67, pi. ii, figs. 4, 4a, 1899. 



Plate XLII. Figures 2, 2a, 2b, 2c. 



Arms very long and slender. Disk five-lobed, the lobes extending 

 out a little on the base of the arms. Teeth three or four; upper one 

 stout, spinifoi-m, the others thicker, subtruncate. 



Whole upper surface of disk and arms and lower surface of disk 

 are covered with thin naked cuticle, wrinkled when diy, containing 

 imbedded, scattered, microscopic scales on the disk, and a row of 

 irregular small, marginal scales. Sometimes there are a few small, 

 irregular granules along the margin and on the under side of the 

 disk, and also on the bases of the arms. Radial shields very small 

 or rudimentary, concealed by cuticle. 



Diameter of disk 7°»°i; length of arms about 45™°^. 



West Indies, 60 to 240 fathoms. 



Oral papillae about five, partly slender, subspiniform, rough at 

 tip, irregularly crowded in a row, nearly equal in length, but some 

 are flattened and obtuse at tip. Sometimes there is also a somewhat 

 stouter tooth-papilla. Within mouth-slits, on each side, there are 

 two (sometimes only one) slender papillfe between the two oral ten- 

 tacle-pores. 



Genital slits wide and open near the oral shields, but narrow dis- 

 tally and not extending to the edge of the disk, bordered by narrow, 

 naked scales. 



Tentacle-pores are small and round. In some specimens there is 

 a small, slender, spiniform tentacle-scale, which is often deeply 

 forked, or even double, and in alcohol is covered with a sheath of 

 cuticle ; it stands nearly in line with the other spines, beside the 



