578 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 83 



tubercles on head, at base of pectoral, and on nape similarly stumpy. 

 Coronet of medium height. Trunk conspicuously slender; snout 

 rather long. First two enlarged spines on tail having short somewhat 

 chunky stumpy appendages, no other filaments, profusely covered 

 with pimplelike excrescences on skin; smaller on side, larger on back. 

 Color nearly uniformly yellowish (probably faded). 



Measurements. — Length 70 mm, with the brood pouch just begin- 

 ning to develop. Depth 12, snout 10.5, postorbital 11, head 24.5. 

 trunk 35, tail 61, and orbit 4.5 percent of length. 



Distinctive characters and relationships. — When I first found the 

 specimen forming the type of the present species, I immediately 

 recognized its striking appearance and set it aside as being distmct 

 from hudsonius, but I hesitated to describe it as a new species on the 

 bare chance of its being an abnormal specimen of that species, since 

 it was taken within the geographic range of that species and the counts 

 of its meristic characters also fall within the range of variation of the 

 subspecies hudsonius. Any doubts as to its distinctive nature were 

 dispelled, however, after I found the three specimens from the Pacific 

 coast that form the basis of hildebrandi. As later noted (p. 582), 

 there is no question that hildebrandi is a distinct species. The most 

 distinctive and striking character of hildebrandi — the structure of the 

 tubercles — is nearly duplicated in the type of obtusus, which is evi- 

 dently the Atlantic coast counterpart of hildebrandi, obtusus differing 

 chiefly in its fewer caudal segments and dorsal rays. 



H. obtusus differs from the other species occurring within its geo- 

 graphic range, hudsonius, as well as from all other American species 

 except hildebrandi, chiefly in the structure of the tubercles, which is 

 very striking. It is one of those characters hard to describe but may 

 be appreciated fully by direct comparison of material. The tubercles 

 in obtusus are very stout and blunt, but they are also low, being 

 reduced to mere stout blunt stumps or knobs. They are unlike the 

 rather slender and notably higher tubercles of hudsonius, or the more 

 or less obsolescent tubercles of hippocampus and reidi. H. obtusus 

 differs further from hudsonius in having a notably slenderer trunk and 

 a longer snout, more so than even the extreme variants of hudsonius 

 of similar size (compare with table 3). The paucity of specimens of 

 obtusus in collections, only the type being known, may possibly be 

 explained by its probable offshore habitat, as discussed in the next 

 paragraph. 



Material studied and distribution. — Oft" Cape Hatteras, N. C; 

 Albatross; June 5, 1885 (84527, the type); the only known specimen. 

 This species possibly has more of an offshore habitat, while hudsonius 

 is common in shallow water inshore and is also taken offshore. 

 There are no available data as to the habitat of the type, but on the 

 day on which it was captured the Albatross was engaged in line fishing 



