OPHIUBANS OF UNITED STATES NATIONAL MUSEUM. 139 



this specimen here and reproduce (pi. 18, fig. 8) an arm piece, because it shows a 

 peculiarity which I did not observe in the specimens which I used as types. In 

 fact, at the level of each brachial article, one of the granules of the upper face is 

 seen to take on a great development and to swell into a large conical nipple with 

 rounded end, which is very conspicuous and very much protruding above the level 

 of the next granules. This peculiarity is observed chiefly at the beginning of the 

 arms. I can but mention this special arrangement, which might perhaps justify 

 the introduction of a distinct variety, if it were found again on other samples. 

 By all its other characters, this individual may be referred to A. elongatum. 



Connections and differences. Among the Astrochema for which A. elongatum 

 might be mistaken, I shall cite chiefly A. clavigerum Verrill, inornatum Koehler, 

 intectum Lyman, and nuttingii Verrill. The distinction between them will be found 

 in the following characters. 



A. clavigerum has protruding radial ribs, which, however, are widened; the 

 upper face of the disk and arms is covered with small, smooth granules which 

 become only a little stronger on the radial ribs without offering those inequalities 

 which I notice in the new species. The internal tentacular scale takes on a remark- 

 able development, and it is, besides, swollen at its end in the shape of a club. A. 

 inornatum has wide and little protruding radial ribs, which are uniformly covered 

 with small granules similar to those on the rest of the upper face of the disk; the 

 upper face of the arms also is uniformly granulous and the granules are always less 

 coarse than in A. elongatum. The arms are shorter and the internal brachial spine 

 is more club-like toward the end; the second spine always appears a little farther 

 away than in A. elongatum, and, as a rule, near the seventh pair, of pores. In A. 

 intectum from Havana, the under face of the arms is altogether bare and as to the 

 tentacular scales there are already two appearing on the pores of the second pair. 

 In A. nuttingii, the pores even of the first pair each carry a tentacular scale, and the 

 second scale appears either on the pores of the second or on those of the third pair. 

 The upper face of the arms offers but a bare tegument with a few very much reduced 

 granules, which, however, become more distinct at a certain distance from the disk; 

 the under face of the disk and of the arms is almost bare. The tentacular mouth 

 pores each bear a little distal scale; the row of oral papillae is more regular and the 

 tentacular scales are longer and narrower. Lastly, the radial ribs seem to be wider 

 and less protruding than in A. elongatum. 



The other species from the West Indies are easily distinguished from A. 

 elongatum. 



