318 BULLETIN OF THE 



Color, in alcohol, light gray. 



Variations. — A specimen with a disk of G mm. had the arm-spines 

 nearly equal (the lowest rather shortest), and three fourths as long as the 

 side arm-plate. In general the middle spine is shortest, but in a consider- 

 able series examined numerous variations were to be seen ; rarely, the 

 spin< s on some part of the arm were equal ; yet, even then, they would be 

 of unequal lengths on other parts. A specimen with a disk of '.'< mm., had 

 the under arm-pl ites comparatively smaller, but still exhibiting in one way 

 or another the characteristic peak or lobe on the outer side; the fourth 

 plate was broad, regular, heart-shape, but with a little point within where 

 the outer sides of the side arm-plates joiner] on the median line ; the tenth 

 plate was similar, but the outer side being wavy gave greater distinctness 

 to the little lobe ; on the upper surface of the disk, a greater proportionate 

 space was occupied by the primary plates, though none of them touched 

 each other; the radial shields were quite separated by two large rounded 

 plates ; the notch of the disk only included a part of one upper arm-plate, 

 and the side arm-plates met above, at the third joint from the disk. In a 

 very young specimen, having a disk only 1 mm. in diameter, nearly all the 

 surface of the upper disk was covered by six large, round primary plates, 

 one in the centre and one opposite each arm ; immediately round the 

 centre plate were five small ones, situated opposite the interbrachial spaces ; 

 over each arm were two very small radial shields like scales, and, in the 

 interbrachial space, on the edge of the disk, a large plate ; finally, there 

 was one more small plate in each interbrachial space, making a total of 

 thirty-one pieces. The notch of the disc was scarcely indicated., and there 

 was no arm-comb. Below, the interbrachial spaces were almost filled by 

 the mouth-shields. The side arm-plates bore three short spines about one 

 third the length of the joint resembling those of 0. albida, and met both 

 above and below, on all the joints; although the upper and lower arm- 

 platen wen; well defined and had nearly their true shapes. 



This species, brought up in numbers from 30 to 125 fathoms, is of high 

 interest ; first, because it seems not to live in company of any species of the. 

 same genus; and secondly, because it much resembles Ophioghjplia albida, 

 so widely distributed in the North European seas and in the Mediterranean. 

 It i<, however, distinguished by the different form of the arm-! pines, arm- 

 comb, and underarm-plates. Ophiogh/pJia Grubei has very similar under 

 arm-plates (if Heller's drawing is accurate),* but differs in the arm-spines 

 and in the curious swelling of the upper arm-plates. Mr. Ljungman kindly 

 examined the specimens and derided that they did not agree with any of 

 the numerous varieties of 0. alb'ula, with which he is familiar He also 



« S ' K.;-. Akad. der Wisseus. XLVT, p. 415, pi. II, figs. 13-16. 



