MUSEUM OF COMPARATIVE ZOOLOGY. 61 



should not be generically distinguished. I have already shown, in considering 

 those of the Hassler Expedition, the very different character of the arms 

 (Figs, 496, 498), and the arrangement of their underlying hard parts is cer- 

 tainly quite ditlerent in the two (Figs. 492, 497). 



ASTROTOMA Lym. 

 Astrotoma Murray! sp. nov. 



Plate XVIII. Figs. 474 - 476. 



Special Marks. — Large tubercles, or smooth warts, on upper side of disk. 

 No booklets on belts of grains on arms, except close to their tip. Clusters of 

 grains in interbrachial spaces next mouth. 



Description of an Individual (Station 194). — Diameter of disk 29 mm. 

 Length of arm 280 mm. Width of arm near disk 7 mm. Height of arm near 

 disk 7 mm Apex of mouth-angle, embracing all the region of the jaw-plate, 

 densely set with short, sharp, nearly equal, spine-like papillae, thirty or more 

 in number, and arranged in transverse rows of three or four. Lower surface 

 and a part of the sides of the protuberant mouth-angles closely set with rounded 

 and sometimes elongated grains. One round madreporic mouth-shield, 1.5 mm. 

 in diameter, lying on the margin of the horizontal mouth -region, where it is 

 separated from the vertical interbrachial space by a fold of skin stretched be- 

 tween the bases of the arms. Arms high, and tapering gradually to their tips, 

 covered above and on the sides by belts of granules alternately raised and 

 sunken. In the former the granules are larger and more distinct, and are more 

 or less regularly arranged in four rows, whereof two at tip of arm bear minute, 

 simple hooks, which, however, are soon rubbed off. In the latter, the granules 

 are minute and arranged as a smooth pavement, in which appear many oblong 

 holes or depressions. On its under surface the arm is covered by a cross- 

 wrinkled, calcified skin, on which are scattered granules. Disk flat and angu- 

 lar, with re-entering curves in the interbrachial spaces : the radial shields, 

 whose outlines are vaguely defined, are broad, and run nearly or quite to the 

 centre. The upper surface is covered by a smooth pavement of small, soldered 

 grains, among which appear small oblong depressions, and on whose surface 

 are scattered a few large, smooth tubercles. The interbrachial spaces below 

 are covered by a clump of large, coarse grains ; at the inner end of each of these 

 spaces is a deep, transverse hollow, at either extremity of which is a short, 

 genital opening. Between the mouth-slit and lower margin of disk there are 

 no tentacle-scales ; but, beyond, each pore has four, rarely five, stout, smooth, 

 peg-like scales, lying side by side, arid nearly as long as an arm-joint ; nearer 

 tip of arm there are but three. Color in alcohol, reddish brown, the disk 

 tubercles and clumps of grains about mouth being darker. 



Station 194, 200 fathoms, 1 specimen. 



