OPHIUKANS OF UNITED STATES NATIONAL MUSEUM. 13 



There is no doubt that this species, which I must consider as a new one, is 

 identical with the OpTiioglypha indicated by Lyman * in 1883, who referred it, 

 together with other specimens, to 0. convexa, and which came from the dredgings 

 of the Blake in the West Indies. Here is what Lyman wrote about these specimens: 



The six primary plates extremely swollen, form an elevated rosette, overhanging very small radial 

 shields, not so large as the head of the genital scale. The mouth shield, too, occupies the whole of the 

 lower interbrachial space. But specimens from station 148 were intermediate, or rather differed from 

 the typical form only in finer arm comb papillae and more interbrachial scales on the disk margin. It 

 will be necessary to await further dredgings before deciding the specific limits. It is to be noted as an 

 important difference, that, while the typical 0. convexa is found in 2,350 fathoms, this species doea 

 not go below 240 fathoms. 



I find again, in the collection of the Ophiurans of the Albatross, two specimens 

 which offer precisely the same peculiarities as Lyman indicated in 1883; it seems 

 to me obvious that these two examples can not be referred to 0. convexa, but that 

 they must constitute a different species the characters of which it is necessary to 

 describe. The disk is pentagonal and even slightly excavated in the interradial 

 spaces; it is thick, but the upper face is little convex; the under face is plane. 

 The arms, rather short, grow rapidly thinner from the base which, besides, is not 

 very wide. 



The upper face of the disk is mostly occupied by six large polygonal plates, 

 contiguous and subequal, arranged as in 0. convexa, but the part of the disk covered 

 by them is still larger than in the latter species. Out of this primary rosette 

 there is to be seen, in each interradial space, but one single large plate, pentagonal, 

 somewhat longer than wide, with a proximal angle widely opened and a distal 

 side lying very close to the outline of the disk; in fact, out of that plate is seen 

 only one other plate which is extremely short and transversally widened. On each 

 side of the large interradial plate, and in its distal region, there are two or three 

 extremely small plates continued on the sides of the marginal plate which 

 succeeds the above-mentioned interradial plate. The radial spaces are entirely 

 occupied by the two radial shields which are in contact with the corresponding 

 primary radial plate, but are much smaller than the latter. 



These shields are a little wider than long; the two in each pair are con- 

 tiguous on their whole length and they form distally an extremely obtuse angle 

 into which is inserted the corresponding angle of the first upper brachial plate. 

 All the plates of the upper face of the disk are covered with pretty fine, rounded 

 granules, which shoot from the angles of a polygonal netting which covers the 

 plates and separates small rounded facets. The radial papillae, visible on the 

 upper face, are extremely elongated and closely disposed, numerous, fine, and 

 sharp; they become rapidly shorter on the under face, and do not extend beyond 

 the level of the distal third of the mouth shield. 



The under face of the disk, in the interradial spaces, is not very wide owing 

 to the widening of the arms at their bases; it is not completely covered by the 

 mouth shields, out of which is left a small space covered by a few polygonal and 

 unequal plates, among which one may be seen occupying a more or less exactly 

 median place, which is a little larger than the others. The genital plates are fairly 



iflull. Mus. Comp. Zool., vol. 10, p. 243. 



