No. IX. ECIIINODERMATA. 275 



perature 29°*5, and also at 25 fins.; Franklin Pierce Bay, 

 15 fms., bottom-temperature 25°*5. 



Coll. Hart : ' Winter-quarters,' Discovery Bay ; Franklin 

 Pierce Bay, 13-15 fms., bottom stony. 



An Ophioglypha with arms very finely tapering, and disk 

 with regularly arranged scales of nearly equal size. Mouth- 

 shields ovate shield-shaped, length less than, or at most 

 only equal to, their breadth; length much less than the 

 distance from the margin of the disk. PapillaB of the disk- 

 incision very short and stout, often grouped. Under arm- 

 plates broadly heart-shaped ; one tentacle-scale. 



This species was obtained at various stations, as indicated 

 in the list of localities ; and though neither the abundance nor 

 the size of the specimens was remarkable, several good series 

 were collected. The characters which have been regarded as 

 6 specific ' are remarkably constant ; and no essential diffe- 

 rence can be traced betweeu these Arctic forms and specimens 

 taken from the coast of Maine, U. S., with which they have 

 been compared, excepting that in the northern Ophiurans 

 the arm -spines are longer and somewhat more delicate, and 

 that the outer margin of the under arm-plates is more 

 arched and the re-entering angle is far less developed, in 

 certain specimens being even altogether untraceable. In some 

 large examples the upper arm-plates are very markedly 

 hexagonal. 



Although this deviation is very constant, the foundation 

 of ' a variety ' on the strength of such characters alone is 

 hardly justifiable. 



The arm-spines are moderately stout and tapering, the 

 upper one being flattened and much larger than the others. 



In most of the specimens under present consideration, the 

 under arm-plates are well separated from one another by the 

 side plates and do not overlap, although in one individual 

 from Discovery Bay the first ten impinge distinctly in conse- 

 quence of their side arm- plates not meeting. This feature at 

 the basal portion of the arm has been noted by Dr. Liitken 

 as occurring in large specimens from Greenland, whilst he 



