210 Bulletin American Museum of Natural History. [Vol. XXXII, 



Ophiura oligopora l sp. nov. 

 Plate XLY, Figs. 8 and 9. 



Disk 9 mm. in diameter (6 in the smaller specimen); arms broken but about 

 22 mm. long. Disk moderately high, especially the radial areas; the center is some- 

 what depressed. Disk covered by some 200 plates, among which the central primary 

 plate and a plate near each interradial margin are rather conspicuous; in the smaller 

 specimen the primary radial plates are also easily made out. Radial shields large, 

 (longer than wide), in contact at middle and clistally, but with outer ends separated 

 by first upper arm-plate and inner ends separated by one or two large scales. All the 

 plates of the disk are thick and many are more or less swollen, but there are no 

 knobs or tubercles developed. Arms rather short, nearly cylindrical. Upper arm- 

 plates tetragonal, the proximal margin less than the distal; outer corners rounded: 

 first three or four plates wider than long but remaining plates increasingly longer 

 than wide; all broadly in contact so far as the broken arms indicate. Interbrachial 

 areas below covered by 30-35 plates. Oral shields larger, longer than wide, penta- 

 gonal with a proximal angle, which the adoral plates adjoin, and the outer corners 

 rounded; genital slits cause a slight reentrant angle on each side. Adoral plates 

 narrow, on proximal sides of oral shields; oral plates about equal in size to adorals, 

 swollen at proximal end. Oral papillae about five on a side; outermost as wide as 

 next two together; only innermost, papillifonn. Genital slits long and conspicuous. 

 Genital scales short and wide distally; broadly visible from above; each scale carries 

 ten or a dozen small papillae, which form a continuous series orally with the minute 

 papillae on margin of genital slit ; aborally the two or three papillae, visible from above, 

 are the largest, but they are inconspicuous and the arm-comb has the appearance of 

 incompleteness. First under arm-plate very large, almost as large as second, wider 

 than long, imperfectly octagonal with rounded corners; second plate pentagonal, 

 wider than long; third plate similar but proximal side very short and distal angle 

 rounded, about as long as wide; succeeding plates wider than long becoming almost 

 spindle-shaped but outer corners rather obtuse; all the plates except first and second 

 (and in the type, the second and third) are separated from each other. Side arm- 

 plates large, broadly in contact beneath but narrowly separated above, at least on 

 basal half of arm; each plate bears three minute, well-spaced, blunt, peg-like 

 arm-spines, of which the uppermost is a trifle the longest. Oral tentacle-pores not 

 opening into mouth-slit, guarded on either side by three or four small scales; on 

 succeeding pores the number of scales becomes rapidly reduced, until on the fifth 

 pore there are only two scales on outer side and one on inner; the seventh pore 

 has one tentacle-scale and after that not even a pore is visible. Color (dried from 

 alcohol), white. 



Type. Cat. No. 00000, U. S. N. M. from Station 5683. 



Comparison of descriptions alone shows that this species is very near 

 0. rugosa Lyman, collected by the 'Challenger' in 700 fms. near Xew 

 Zealand. Comparison of specimens of the same size however, reveals 



1 6X170? = few + Ttopos = pore, in reference to the reduction of the tentacle-pores. 



