OPHIURANS OF UNITED STATES NATIONAL MUSEUM. 101 



with extremely small, dense, and regular denticulations; these denticulations appear 

 almost on the whole length of the spines, excepting just near their basis, and they 

 become a little stronger toward the end. The length of the spines increases from 

 the first ventral, which reaches or even exceeds one-and-a-half articles, to the 

 last dorsal one which equals at least two-and-a-half articles; this latter spine is 

 often narrower than the others. On the large specimens one often finds seven 

 spines on the first articles, then they fall back to six and finally to five. 



The tentacular scales first amount to two, a figure which is maintained over 

 a certain length of the arms, sometimes even over three centimeters, then, after 

 some irregularities, there finally remains but one tentacular scale. The external 

 scale is always much more developed than the internal one; it is large, triangular, 

 very much widened at the base and its end is pointed except on the first articles 

 where it is wider and almost oval; the surface is rough. The internal scale, partly 

 covered by the foregoing one, is shorter and narrower and its apex, which is less 

 pointed, often offers one or two little spinules. These two scales extend regularly, 

 with the characters I have just described, on to a certain number of articles; then, 

 at a variable distance from the base of the arms, the internal scale is seen to dis- 

 appear, either on one side or on the other, or on both sides at the same time, then 

 it appears again a little further on to disappear again and sometimes to reappear 

 once more, all of it in a very irregular manner. Sometimes after a large number of 

 articles which show but one tentacular scale on each side, one sees the internal scale 

 suddenly appear again on a single article, either on the right or on the left. Be it as 

 it may, the external scale finally persists alone until the end of the arms. The pores 

 of the first pair have sometimes three scales which are then smaller than the two 

 normal ones. 



The color of the specimens in alcohol is a light brownish-yellow identical with 

 what is known in 0. valenciennesi, but that from station 2348 is simply greyish. 

 One can still trace two fairly wide longitudinal lines, of a somewhat darker brown, 

 which run on each side along the upper median line of the arms. 



Connections and differences. This species is very interesting, because, as I have 

 pointed out above, it recalls both Ophiopristis ensifera and Ophiacanfha (Ophiotreta) 

 valenciennesi. The arrangement of the oral papillae does not permit its being 

 classified in the genus Ophiopristis of Verrill, but the shape of the upper and under 

 brachial plates, as well as that of the mouth shields, the presence of fairly large 

 radial shields and the armature of the plates of the upper face of the disk consisting 

 of small and short echinulated spines, recall Ophiopristis ensifera. 0. affinis 

 is near the few species classified by Verrill in his subgenus Ophiotreta, and chiefly 

 near 0. valenciennesi with which it was even associated at station 2321. It plainly 

 differs from the latter species by the tentacular scales, two of which appear on a 

 certain part of the length of the arms and have quite a different shape, by the 

 mouth shields being large and broadly widened instead of small and elongated, 

 by the scales of the disk being armed with real little spines instead of mere granules, 

 by the brachial spines being beset with denticulations over their whole length 

 and not only in the terminal part, and chiefly by the shape of the external oral 

 papillae which are hardly different from the preceding ones. Owing to this latter 

 character, 0. affinis has its place just at the limit of the genus Ophiotreta. 



