HALEC. 53 



1, G, pinx.) 18 extremely .slender, terminating in trout in a small triangular 

 expansion, which is longer tluui deep. This expaiisicjn is well shown from the 

 inner side in fig. 7 ; while its outer face is seen in many specimens {<'.<J., B. M. 

 nos. 49082, P. 1)252) to be ornamented with close rows of tubercles which slightly 

 radiate from its pointed anterior end. The entire length of the oral margin of the 

 bone is ornamented with a cluster of much finer tubercles, which seem to pass 

 almost imperceptibly into the minute teeth. The latter are conical and slender, 

 and arranged in a single, uniform, close series, with their apices slightly inclined 

 backwards. The maxilla (figs. 1, 6, mx.) is also very long and slender, and its 

 narrow exposed edge is ornamented with minute tubercles. A considerable length 

 of its hinder portion enters the gape of the mouth, and bears a regular, well-spaced 

 series of five to seven rather large conical teeth, which are slender, straight, 

 sharply pointed, and inclined forwards. The hinder two fifths of the maxilla are 

 deeply overlapped by the large supramaxilla {amx.), which is pointed in front and 

 deepest at its rounded hinder end, where it curves slightly upwards. The maximum 

 depth of this bone equals less than one third of its length ; and its outer face, 

 except along a narrow margin at the upper edge, is ornamented with fine tubercles, 

 which are arranged in rows chiefly radiating from a point near the hinder end. 

 The length of the mandible is five times as great as its maximum depth ; but its 

 lower portion curves so nmch inw^ards that, when uncrushed, its true depth is not 

 seen in dii-ect side-view. The very large dentary bone {d.) tapers to a point at the 

 symphysis, where its lower or inner edge is apposed to that of its fellow of the 

 opposite side for some distance (fig. 5 a, s.). Its outer face, crushed completely 

 into view, though flaked, in the original of fig, 1, bears a very fine tubercular 

 ornament, which is partly disposed along some structural lines radiating from the 

 symphysis, and is entirely absent along an elongate-triangular smooth area just 

 below the hinder half of the tooth-bearing border. The mandibular teeth (fig. 5, d.) 

 are slender and conical, rounded in section, and with a large central cavity. They 

 form an irregular narrow cluster along the dentary border, quite small at the 

 outer edge, but as large as the opposed upper teeth within. The short articulo- 

 angular bone (figs. 1, 5 a, ag.) is ornamented in its lower portion with I'ows of fine 

 tubercles which radiate forwards from its articular end ; while its smooth upper 

 part is a direct continuation of the smooth area of the dentary bone. The general 

 aspect of the jaws is diagrammatically represented in Text-fig. 11, p. 51. 



The preoperculum (figs. 1, 8, l^p.) is deep and narrow, almost without a lower 

 limb, but produced at its angle into a short and deep, posteriorly directed s])ine, of 

 which the pointed apex is broken in the original of fig. 1. The exposed face of 

 the lower end of the bone, with its spine, is ornamented Avith the usual rows of fine 

 tubercles so characteristic of the fish. The operculum (fig. 8, op.) is nearly 

 rhombic in shape, with its postero-inferior angle produced into a short broad spine, 

 which is strengthened by a horizontally directed ridge on the inner face of the 



