ARCTIC SEA TO THE WEST OF GREENLAND. 67 



Description of the Illustrations of this Species on Plate IV. 



Fig. 8. The upper surface : slightly magnified. 



9. The scaling of the upper part of the disk and part of the arm : magnified. 

 10. Part of the underpart of the disk: magnified. 

 14. Part of the disk-scaling : magnified. 



Genus AMPHIURA, Forbes. 



AmpJiiura, Forbes, Linn. Trans, vol. xix. 1842. 



Disk small and delicate, covered with naked overlapping scales, and furnished with 

 uncovered radial shields. Teeth: no tooth-papilla;; six (rarely eight) mouth-papillae 

 to each angle of the mouth. Arms slender, even, more or less flattened. Arm-spines 

 short and regular along the sides of the arm-plates. Two genital slits. 



AMPHIURA HOLBCELLI, Liitken. Plate IV, Figs. 15-17. 



Ampliiura Holbcelli, Liitken, Vid. Medd., Nov. 1854, p. 98. 



The mouth-papillae are six to each angle of the mouth (the two innermost stoutest 

 and pointing to the centre of the mouth), and are oblong and running upwards towards 

 the teeth. The innermost papilla is attached to the side mouth-shield ; it is small, flat, 

 with a curved cutting-edge, and is long and sharp like a canine tooth. Teeth four : 

 two uppermost large, flat, longer than broad, squarish, rather thick, presenting a broad 

 free surface. Mouth-shields rounded, truncated, and narrower without ; and madreporic 

 shield the largest, and with pores on its edge. Side mouth-shields large, broad, and 

 triangular, with all their sides reenteringly curved, meeting within, and also their 

 neighbours, between the first and second under arm-plates. 



Only a single specimen ofAmphiura was taken in high latitudes ; and this, although 

 it differs slightly from the type form in the relative measurements of certain points of 

 detail, we have little hesitation in assigning to Dr. Liitken's species, the variations, in 

 our opinion, not being of greater importance than such as we should regard as dependent 

 on locality and conditions of life. 



The solitary specimen was found in Franklin-Pierce Bay in 15 fathoms, the tempe- 

 rature being 29 0- 5 Fahr., and presents the following characters : 



An Amphiura with disk lobed ; radial shields long and narrow ; mouth-shields 

 rounded ; side mouth-shields large, subtriangular, with the sides reentering and angles 

 rounded. Three pairs of mouth-papillae, the middle ones placed higher than the others. 

 Under arm-plates pentagonal. One tentacle-scale, rounded. Arm-spines three or four. 



The arms are less broad, and take their origin in a more deeply reentering curve of 

 the disk-margin ; the radial shields are narrower ; and the breadth of upper arm-plates, 

 in proportion to their length, is less than in the type forms, as the following measure- 

 ments will indicate: Diameter of disk 8 millims. ; radial shield, length 1-3 millim., 

 breadth 0'35 millim.; sixth upper arm-plate, length 0'6 millim., breadth 0-9 millim. 

 The spines are hollow cylinders, stout, blunt, and but slightly tapering; the upper spine on 



K2 



