ABCTIC SEA TO THE WEST OF GREENLAND. 61 



which primitive tooth-papillae may have been developed ; nor is such an assumption 

 by any means extravagant when the great irregularity of these parts amongst Arctic 

 forms is taken into consideration. 



The specimen of Ophioglypha Sarsii, the teeth of which have been alluded to as 

 being abnormal, is dry and of a dirty white colour. The disk has a pentagonal outline 

 above, but is circular below ; the notches for the arms in the upper part of the disk 

 are distinct ; and the scaling is small. There is a small circular scale centrally ; and 

 the radial shields are embedded, as it were, except at their outer extremity. Several 

 scales separate the radial shields, some being larger than the others. The radial shields 

 are separated aborally, by a linear groove, from distinct radial scales. These bear the 

 majority of the flat, broad, closely-set spinules, which are continued on the interbrachial 

 space below, along the generative slit, and finally touch the sides of the mouth-shield. 

 A corresponding series of much smaller, adpressed and blunt spinules is on the side 

 arms close to the others ; and it can be traced, as a ragged dentate border, to the generative 

 slit, close to the arm on the under surface of the disk. Three or four small upper arm- 

 plates exist before the full-sized fifth is seen ; and they are more or less within the 

 notch ; and their aboral edges are very faintly incised. Below, the mouth-shields have 

 the usual shape of those of the species, and the side mouth-shields are small, and their 

 outer and aboral part is in contact with the generative slit. About six close, short, 

 blunt scales are on each, and are opposed to a smaller number of slightly larger 

 tentacle-scales on the arm ; and the tentacular opening (the 1st visible but the 

 2nd really) is long. The jaws are very short, stout, and lumpy inferiorly ; and the jaw- 

 plate is small. The mouth-papilla?, usually so symmetrical, are placed obliquely, are 

 irregular; and the usual central one is replaced by from four to six smaller ones, 

 which have been noticed before. The underpart of the side arm-plates near the 

 disk somewhat resembles that of Ophioglypha lacertosa, Forbes, sp., being almost 

 perforated where the oral angle of the under arm-plate nearly or quite touches the 

 aboral edge of its predecessor. Union of the side arm-plates below, occurs at about 

 the sixth or seventh. The three arm-spines are small, irregular in shape, are adpressed, 

 rounded, and rather flat ; sometimes a fourth is seen ; and all are slightly constricted 

 above their origin. Two tentacle-scales exist to the end of the arm ; but in some 

 joints there are three, or even four, small scales. In mid arm the tentacle-scales are 

 on the side arm-plates only ; one is short, broad, flat, and narrowed at its origin, and 

 is internal to the other. Each either resembles a small conico-cylindrical spine, or is 

 more like the first. In the neighbourhood of the disk the narrow peduncled and 

 broad, short, blunted tentacle-scales, normally two on the side arm-plate over the 

 tentacular opening, have a third, placed flat against the under arm-plate, from which 

 it springs. Nearer the oral opening, the number of tentacular processes increases as 

 usual. Where only one tentacle-spine exists, it is broad, and appears to be double with 

 a common base. 



Description of the Illustrations of this Species on Plate IV. 



Fig. 3. Ophioglypha Sarsii, Liitken, the top : natural size. 



4. Ophioglypha Sarsii, Liitken, the underpart of the disk. 



