of the Island of Trinidad^ W. 1. 37 



slight curve, to the snout; this curve is boldest between the 

 interparietal projection and the dorsal spine ; from the former 

 point to the snout, it is nearly straight. The whole surface of 

 the casque is pitted ; the indentations are generally more 

 numerous and approximated on the anterior plates, than on the 

 posterior ones ; and are there separated from each other only by 

 the broad and elevated lines of the surface, which, by their 

 frequent intersection, give a coarsely reticulated appearance to 

 the casque. The interspace between the interior margins of the 

 anterior frontals, or the " solution of continuity" of Valenciennes, 

 is generally large, of an ovate-fiisiform shape, and extends from 

 the anterior angle of the interparietal, (where it is sometimes 

 slightly rounded, the interparietal being proportionally emar- 

 ginated, or truncated) to within a short distance of the bare skin 

 of the muzzle, from which it is generally separated by the inter- 

 vention of a small sub-triangular plate, whose apex is posterior. 

 Occasionally this plate is absent, and the bare skin of the 

 muzzle is continuous with that of the interval between the 

 frontals ; this interval is also variable in its proportional length, 

 sometimes being thrice as long as it is wide, and at other times 

 not more than twice its width. The eyes are circular and of 

 moderate size, the diameters of the orbits forming about a 

 sixth of the entire length of the head ; they are separated from 

 each other by about three and a half, and are at a distance 

 from the snout of about two and a half diameters. 



This description applies equally to the males and the females. 

 We now proceed to describe the sexual characters and differ- 

 ences ; these are chiefly manifested exteriorly in the spines of 

 the pectorals, and have afforded to Valenciennes the charac- 

 ters which distinguish two of his nominal species, the Callich- 

 thys laevigatus, and the C. subulatus. 



In the males, or those described by Valenciennes as Oal- 

 lichthys subulatus, the spines of the pectoral fins are stout; 

 externally, arni on the superior borders, they are covered by 

 rasp-like asperities; internally, they are nearly smooth ; a smooth 



