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U. 8. P. R. R. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



The body, as already stated, resembles that of Gunnellus to a very high degree ; it is very 

 much compressed, deepest upon its anterior third, and diminishing gradually backwards. The 

 thoracic region itself tapers towards the head, which is sub-conical and contained about seven 

 times and a half in the total length. The mouth is proportionally large and its gape nearly 

 horizontal. The posterior branch of the maxillary is curved rather abruptly downwards, its 

 posterior extremity falling evenly with a vertical line intersecting the posterior rim of the eye. 

 The teeth are conspicuous ; upon the extremity of both jaws we notice sub-conical, nearly erect, 

 teeth, much larger than the rest, and which we have designated as the canines. Two may be 

 seen upon the upper jaw and four upon the lower, the outermost of which being much larger 

 than the inner, and larger also than those of the upper jaw. 



The branches of the jaws exhibit each one series of sub-conical teeth, largest upon the middle 

 of the series. Upon the upper jaw (premaxillaries) we observe a second and inner series of 

 much smaller, more numerous, and very slender teeth. The eye is sub-circular, its diameter 

 entering nearly five times in the length of the side of the head. There are six slender branchi- 

 ostegal rays on either side, and the branchial apertures being continuous under the throat 

 without longitudinal splitting towards the hyoidian apparation. The dorsal fin commences at 

 a short distance from the occiput, is quite low and composed of spiny rays exclusively, and 

 terminates at the base of the caudal to which it is contiguous. The anal, on the other hand, is 

 composed exclusively of very slender, soft, and articulated rays, being likewise contiguous to 

 the caudal. Its origin is situated a little nearer the end of the snout than the extremity of the 

 caudal fin. The latter is moderately developed and rounded upon its periphery. The ventrals 

 are wanting, and the pectorals quite diminutive. 



We can detect no traces of scales ; but we observe three lateral mucous ducts extending from 

 the head to the base of the caudal fin ; they are equidistant, though the upper and the lower 

 approximate more the dorsal and ventral outlines than the middle one. A fourth duct may be 

 seen extending from the base of the pectoral fin to the vent ; it is connected to its neighbor of 

 the sides by a common branch which, from under the pectorals, extends to the hyoidian apparatus. 

 The two uppermost ducts are connected anteriorly by a thoracico-occipital bent, which from the 

 middle of the occiput sends a branch to the origin of the dorsal fin. All these ducts have small 

 alternating lateral branches, which correspond to the myocoms of the great lateral muscle. The 

 main ducts themselves occupying the bents or curvatures of those very same myocomma. The 

 opercular bones and jaws are very porous also. 



The ground color is dark olive ; dorsal region and posterior half of the body clouded, macu 

 lated or marmorated with brown or blackish brown. Abdomen unicolor. Two post-ocular 

 blackish vittae may be seen crossing the cheek. 



List of specimens. 



