MUSEUM 01* COMPARATIVE ZOOLOGY. 343 



of the lower arm-plate, as 1.1, 1.1, 1.3, .9, .7, .G, .G, .5:. 3. Seventh joint 

 longest spines, .5 mm., and the rest are not much shorter. On the first two 

 or three joints beyond the disk the two ranges of spines meet on the median 

 line of the arm above. The second arm-joint has but three spines, and of 

 these the lowest is, as an exception, longest, namely, .G mm. Tentacle scales 

 blunt, pear-seed shape, the apex outward , further out on the arm they grow 

 more pointed ; their length is about half that of the under arm-plate. The 

 color, in alcohol, is pale brown for the disk, and light straw for the arms. 



Variations. — The chewing apparatus shows few exceptions : sometimes, 

 however, the central inner mouth-papilla is somewhat narrower than the 

 teeth above it : very rarely one of the small, side mouth-papilla; is wanting. 

 The number and lengths of the disk spines is not always the same; and 

 especially are those near the margin sometimes shorter. In the lamer 

 specimens the second joint has four spines. 



Among numerous specimens there was found one that had scarcely any 

 spines on the disk, and those very short; while the radial shields were 

 buried by the disk scales, except their outer ends. The arm-spines were 

 essentially the same; on the fifth joint, lengths to that of the under arm- 

 plate, 1., 1., .8, .8, .8, .G, .G, .5.: .3. 



Numerous specimens, in 15 to 135 fathoms. 



Ophiornyees Lyman, gen. nov* 



Teeth: no tooth-papillae ; numerous wide, flat mouth-papilla?, which are 

 turned downwards and outwards, and arranged in two or more imbricated 

 rows, covering the whole mouth-angle. Side mouth-shields large, and 

 meeting above. Disk finely scaled, without visible radial shields. Arm- 

 spines within the disk shorter, stouter, and of a different character from 

 those of the joints further out. 



This singular genus stands quite by itself, unless we compare its curious 

 mouth-papilhe with the spatula-like tentacle scales of Opldopsila. All the 

 specimens I have seen had a tendency to raise the arms above the disk, 

 vertically ; which shows that the muscular tension must have some peculiar 

 proportion. 



Ophiornyees rnirabilis Lyman. 



Special Marks. — Six arm-spines, nearly equal; on the second joint 

 a connected row of ten short, ll it arm-spines, running across the under 

 side of the arm. two of these spines being on the under arm-plate, and four 

 on each side arm-plate. 



Diameter of disk about G mm. Length of arm 17 mm. The inner 

 mouth-papilla: are rounded, sharp, spinifoffla, and eight or ten in number; 



* 6£i?, a snake; fiv/cTj?, a mushroom. 



