74 



U. S. p. R. R. EXP. AND SURVEVS ZOOLOGY — GENERAL REPORT. 



posterior marj^in, constitutes about the seventh of the total length. The origin of the ventrals 

 takes place on a line immediately behind the base of the pectorals. Their extremities extend 

 beyond the origin of the anal fin, consequently overlapping the vent. The second articulated 

 ray is longer than the rest. The extremity of the pectorals corresponds to a line intersecting 

 the origin of the anal fin. 



Br. VI : VI ; D XXI, 13 ; A III, 17 ; C 3, 1, 6, 5, 1, 2; V I, 5 ; P 14. 



The scales are very small, firmly imbedded in a tough skin. Their structure is very simple : 

 neither concentric lines nor radiating furrows ; a uniform granular appearance of the entire scale 

 is exhibited under the microscope. Tlie comb- like posterior margin is provided with a variable 

 number (from four to eleven) of processes, too large to be called cilise ; these are the only parts 

 protruding from the skin, giving the body a shagreened appearance, and quite rough to tlie 

 touch. The lateral line is concurrent with the dorsal outline, but is not composed of any 

 particular scales. The upper surface and sides of the head are covered with minute scales similar 

 in structure to those of the body. The snout alone is smooth. There are no scales on the base 

 of the fins. 



The head and body are of a soiled yellowish-brown hue, darker above than beneath. The 

 base of the dorsal fins is maculated with black ; the caudal and jjectorals, barred with the same ; 

 and the anal and ventrals are uniformly black upon their external half, the edge of the fins 

 alone being whitish. 



References to ilie figures. — Plate XVII, fig. 5, represents Zaniolepis latipinnis, reduced from 

 a specimen nine inches long. Fig. C is a scale from the middle of the flanks, considerably 

 magnified. 



List of specimens. 



NAUTICHTHYS, Girard. 



Gen. Ciiak. — Upper surface of head and opercular apparatus spinous. Mouth moderate, with its gape nearly horizontal ; 

 the jaws being sub-equal. Velvet-like teeth upon the premaxillaries, dentaries, front of vomer, and palatines. Gill aper- 

 tures separated under the throat by an isthmus; brancliiostegal rays, five on either side. Dorsal fins contiguous upon their 

 base ; first one shorter than the second. Caudal fin posteriorly rounded. Ventrals slender and elongated, inserted under the 

 base of the pectorals, which are large and broad, with the infeiror rays projecting beyond the interradial membrane. Skin 

 studded with minute prickles. 



This genus, like the preceding, is related to Blepsias and Trachidermis, by its prickly skin. 

 From the former it differs by the absence of membranous or filiform appendages, recalling to 

 mind Scorpama ; by its anterior dorsal, which is higher than the second ; by the depth of the 

 anal which is less deep than the second dorsal is high ; by the branchial apertures, which are 

 separated by a wide isthmus ; and by its ventrals, which are longer and more slender. Its true 

 affinities with Trachidermis we are not prepared to trace, since no specimens of the latter are at 

 our command. 



