8 LYMAN ON A NEW STRUCTURAL 



second mouth-tentacle, while the opposite margin, formed by a portion of the side mouth- 

 shield, bears two flattened, spine-like tentacle-scales. Mouth-shields small and of a rounded 

 heart-shape ; length to breadth, 1:1. Side mouth-shields small, wide without, but narrow 

 and not meeting within. First under arm-plate pretty large and wide, three-sided, with an 

 angle inward. Those beyond are shaped like an axe, with a wide, curved cutting-edge, 

 and a narrow body pointing inward. The narrowness of the inner portion comes from the 

 encroachment of the large tentacle-pores. Side arm-plates long but not prominent ; meet- 

 ing above and below. Upper arm-plates small and triangular with an angle inward. 

 Disk thin and flattened, with a tender skin covered by very thin, dehcate, overlapping 

 scales ; two or three in the length of 1 m.m. No radial shields can be seen from the 

 outside. There are apparently large genital openings, but these are merely the creases 

 on either side of the arm ; for, in reality, the under disk surface, with a very delicate 

 scaling, is continuous over the arm, and there are no genital openings in their usual 

 position. Four delicate, sharp, somewhat flattened, arm-spines which, though placed on 

 outer edge of side arm-plates, have a considerable lateral motion. No tentacle-scales 

 except to the mouth-tentacles. 



Color in alcohol ; disk, pale greenish-gray ; arms, straw. 



" Challenger," Station 157, east of Kerguelen Islands ; 1950 fathoms ; 1 specimen. 



Ophiochttra ^ gen. nov. 



Disk covered with little, overlapping scales, and small radial shields. Teeth : no tooth- 

 papillae : a line of squarish, close-set mouth-papillae on each side. Large side arm-plates, 

 which meet above and below, and bear on their outer edge small spines, which, however, 

 stand at nearly a right angle to the arm. 



Ophiochytra epigrus sp. nov. Plate II, figs. 17-19. 



Special marhs. Two small peg-like arm-spines. One tentacle-scale. Very small 

 radial shields, wider than long. 



Description of an individual. Diameter of disk, 5.5 m.m. Length of arm about 

 13 m.m. "Width of arm, without spines, 1.2 m.m. Teeth small, wide and short, closely 

 soldered to a small and very thin jaw-plate. On either side of mouth-angle, a close row of 

 three or four flattened, squarish mouth-papillae, whereof the outermost is largest and acts 

 as tentacle-scale to the second mouth-tentacle. Mouth-shields small, of a pointed heart- 

 shape, with the angle inward ; length to breadth 0.8 : 0.6. Side mouth-shields long, and 

 extending far beyond the mouth-shields, tapering inward where they nearly or quite meet. 

 First under arm-plate about as broad as long, with a curved, or slightly angular outer 

 side, and a tapering angle inward ; the plates beyond are axe-shaped, much wider Avith- 

 out than within, bounded without by a curve, on the lateral sides by reentering curves, 

 and within by an obtuse angle. Side arm-plates long and meeting broadly above and 

 below, thickened on their outer edge, but not flaring. Upper arm-plates small, with three 

 nearly equal sides, and an angle inward. Disk round, slightly arched, covered above with 

 pretty regular, rounded overlapping scales, two or three in the length of 1 m.m.; and below 



1 '0(iir, a, snake; x^rpa, a flat vase. 



