GONATODUS PUNCTATUS. 95 



none is the extreme point of the upper lobe of the tail preserved. The length of the 

 head is contained about four times, the greatest depth of the body about three times in 

 the total length up to the bifurcation of the caudal fin. The head is short, with bluntly 

 rounded snout ; the external ornament of the bones of the cranium proper is rugose in 

 character. The operculum is oblong, broader above than below, and ornamented with 

 delicate ridges which radiate from the anterior superior angle downwards and backwards 

 over its surface; the suboperculum is nearly square, and marked with ridges, which for 

 the most part pass horizontally over its surface from before backwards ; the preoperculum 

 is well developed. 



Of the other bones of the head, those of the jaws demand special attention. The 

 maxilla (PI. XIX, fig. 2) resembles in form that of the species of Elonichlhys, the 

 inferior or dentary margin being gently curved downwards behind the region of the 

 orbit, the anterior part of the superior margin falling away gradually downwards and 

 forwards into the upper border of the sub-orbital process, while the posterior margin is 

 obtusely angulated below the middle ; the broad or post-orbital part of the bone is 

 ornamented with delicate branching and anastomosing ridges, which for the most part 

 tend to run parallel with its posterior and superior borders. In fig. 3 we have the inner 

 surface of the dentary element of the mandible ; the outer surface of this element is 

 covered with a close striation, the ridges running longitudinally, but the dentary margin 

 is finely tuberculated. 



The teeth with which the jaws are armed are about -^jth to -^th of an inch in 

 length, slender-cylindrical in shape, but near the extremity suddenly narrowed to a 

 sharply conical apex. Each tooth (fig. 4) is first inclined a little inwards, then bent 

 outwards at an obtuse angle, and again bent so that the apex comes to point upwards 

 (or downwards in the case of the maxillary teeth). They are nearly uniform and 

 arranged in a closely set row, nor have I seen evidence of smaller ones outside. But in 

 the lower jaw, as pointed out by the late R. Walker, the teeth are very often placed 

 alternately, one close to the outer margin, and the next to it a little further in, and so on 

 the whole length of the range. 



The branchiostegal rays or plates are thirteen on each side (PI. II, fig. 4, br.), the 

 anterior of each series being broader than those behind, and besides these there is a 

 median lozenge-shaped plate in front. The parasphenoid bone has likewise been 

 already figured and described in a previous part of this Monograph (p. 16, PI. II, fig. 5). 

 The bones of the shoulder-girdle are well shown in most of the specimens, and like 

 those of the face are ornamented externally with flexuous branching and anastomosing 

 ridges. 



The scales of the flank (PI. XIX, figs. 5 — 7) are slightly higher than broad, with 



gently concave upper and convex lower margin ; the articular spine is well marked, 



On the under surface (fig. 6) the socket for the spine of the scale below is distinct, but 



the keel is nearly obsolete; the latter appears as we proceed backwards towards the tail, 



14 



