106 BULLETIN 84, UNITED STATES NATIONAL MUSEUM. 



The first under brachial plate is fairly large, trapezoidal, with the proximal 

 side widened and slightly excavated in its middle the lateral sides are oblique and 

 they meet by rounded angles a small distal side; this plate is somewhat longer than 

 wide in the smaller sample and, on the contrary, it is a little wider than long in the 

 larger one. The next plates are large, pentagonal, with a proximal angle, which is 

 still fairly well delineated on the second plate, but which afterwards becomes very 

 obtuse; the lateral sides are narrow and the distal side is very wide and slightly 

 convex. These plates are always much wider than long, and they are separated 

 from the basis of the arm by an interval which becomes fairly long from the second 

 plate upward. 



The lateral plates are fairly protruding and they carry nine spines each at the 

 basis of the arms; the two rows on each side are very much approximated dorsally. 

 The length of the spines increases from the first ventral one, which is shorter than 

 the article upward, to the last two dorsal ones; the latter scarcely exceed one and a 

 half articles at the basis of the arms, and afterwards become much shorter. 

 These spines are thin, cylindrical, and pointed; they are provided with fine and 

 dense denticulations, which are particularly obvious on the ventral spines, and less 

 so on the dorsal side. 



The tentacular scale is small, conical, with a blunt point, and its surface is 

 rough. 



Connections and differences. Ophiomitretia levis seems to me to be very near 

 0. Isevipellis (Lyman), which it recalls by its small size, by the shape of the upper 

 and under brachial plates, by a like arrangement of the mouth pieces, etc. It 

 differs from it in having the covering of the disk made of stumps regularly ending 

 in a diverging bunch of minute spinules, whilst in 0. Isevipellis these plates carry 

 only some rounded globules which seem to be much caducous, for the plates are 

 most often bare; the oral papillae regularly amount to three in the two examples of 

 0. levis which I had in hand, whilst in 0. Isevipellis they vary in number even in the 

 same specimen. Lastly, the brachial spines are more strongly echinulated than 

 in the new species. Though 0. Isevipellis is likely to offer certain variations, which 

 have been studied chiefly by Verrill (99 a, p. 343), these variations are of a kind 

 which does not allow of 0. levis being united with 0. Isevipellis; especially the cover- 

 ing of the upper face of the disk remains as a most striking characteristic of the new 

 species. 



OPHIOMITRELLA L.EV1PELLIS (Lyman). 



Plate 13, figs. 4-5. 



Ophiawntha Ixvipellis LYMAN (83), p. 259, pi. 6, figa. 82-84. 

 Ophiomitrella Isevipellis VERRILL (99), pp. 39, 43. 

 Ophiomitrella Ixvipellis VERRILL (99o), pp. 326, 332, 343, and 362. 



Albatross station 2159. Apr. 30, 1884. Lat. 23 10' 39" N.; long 82 20' 

 08" W.; 98 fathoms; co. A single specimen. 



The diameter of the disk is only 5 mm. The specimen is rather incomplete; 

 two arms are completely lacking and the others are only partly preserved. The 

 example is quite in conformity with VerrilTs description, which has completed and 

 corrected Lyman's, and the very small granules of the upper face of the disk are 

 very few; I have, besides, compared it with a specimen determined by Verrill 

 which has been sent to me by the United States National Museum. 



