GLYPTOL^MUS KINNAIRDI. 



45 



The ventral part of the pectoral arch is represented, on each side, 

 by two broad, triangular, somewhat curved, bones. The anterior 

 one meets its fellow in the middle line, just behind the posterior 

 edges of the principal jugular bones ; but their inner margins imme ■ 

 diately diverge, passing backwards and outwards, and being 

 continued in the same direction as far as the posterior edge of the 

 operculum, by the inner edge of the posterior pectoral plates. The 

 adjacent margins of the two plates seem to be firmly united toge- 

 ther, and their outer surfaces exhibit a marked sculpture, whose 

 ridges are more evenly continuous than those of the cranial bones. 

 Two large triangular scales which fit in between the supraoccipital 

 and the epiotic appear to represent some of the upper elements 

 of the pectoral arch. 



The pectoral fins are not perfectly displayed in any specimen, but 

 fig. 2, Plate II., shows that they were well developed, being 

 about as long as the head, and that they were provided with nume- 

 rous long and delicate fin rays which beset the edges and extremity 

 of a stout central stem, covered with rhomb oidal scales. 



The ventral fins, smaller than the pectorals, were also, as figs. 2, 3, 

 Plate I., show, distinctly lobate, their central stem being covered 

 with' rhomboidal scales and terminating in a point, at about the 

 middle of the length of the fin. 



The median fins present very distinct jointed fin-rays, and, as 

 may be seen in fig. 1, Plate I., the scales of the body are con- 

 tinued on to the bases of the dorsals and anal, so as to give them, 

 though to a far less degree, the lobate aspect of the pectorals and 

 ventrals. 



Both dorsals are pointed at their extremities, and somewhat fan- 

 shaped, from being narrower at their bases than in their posterior 

 moieties. The first dorsal is smaller than the second. The anal 

 fin, opposite the second dorsal, is about as large as the latter, and 

 has the same slightly lobate aspect. 



The rhomboidal caudal fin, whose rays commence almost immedi- 

 ately behind those of the second dorsal and anal, is perfectly 

 symmetrical, the axis of the tapering extremity of the body being 

 not only free from any upward inflexion, but corresponding with 

 the " equator of the fin. 



The scaly extremity of the body appears to stop at some distance 

 before reaching the posterior margin of the fin, but it is difiicult to 

 make quite sure of the fact. 



The scales are thin, and exhibit a sculpture of variable appeai- 

 ance, but always made up of raised ridges, with intervening valleys 



