92 GANOID FISHES OF THE CARBONIFEROUS FORMATION. 



ridges ; on the mandible the lowermost ridges run forward parallel to the lower border of the bone, 

 whilst the uppermost ones run forwards — the most anterior ones branching — and upwards to cut the 

 dentary margin of the bones at a very acute angle. 



"The scales of the fish are sculptured in a very striking aud beautiful manner, which varies some- 

 what on the various parts of the body, viz., on the principal flank scales the ornamentation is of a 

 duplex pattern, viz., below a line drawn from the anterior superior angle to the posterior inferior angle 

 are well-marked ridges which run from the anterior border downwards and backwards, converging 

 towards the posterior inferior angle, above the diagonal line fine ridges, which run in a more or less 

 irregular manner towards the posterior border, while several very flue ridges run close to and parallel 



the superior border. Further back on the flank there are often several fine ridges running parallel 

 to the inferior as well as the superior margin, whilst between these the coarser ridges run in a more or 

 less irregular manner towards the posterior border, which appears to be somewhat serrated. On the 

 lower ventral scales there are firstly several well-marked ridges running obliquely downwards and 

 backwards from the anterior to the inferior border, whilst behind these are — on the greater part of the 

 scale — ridges which ruu posteriorly more or less parallel to the superior and inferior margins. The 

 general character of the scale sculpture is continued far back towards the caudal region. The median 

 dorsal scales are ornamented by ridges which run in a regular manuer backwards and inwards — on 

 each lateral half of the scale — to meet along the median line. 



"No fins — with the exception of some rays of the caudal — are seen. The rays of the caudal fin 

 appear to have been somewhat distantly articulated." 



The type specimen and other fragmentary remains from the " D Shales," Millstone 

 Grit, Summit, Lancashire, are in the collection of Mr. Wellburn, who considers that, 

 though the first is distinct as a species, some of its scales somewhat resemble those of 

 Elonichthys Robisoni (Hibbert), as figured by me on PI. XIV, figs. 5 and 0, of this 

 Monograph. 



Genus — Gonatodus, Traquair, 1877. 

 Amblyptekus (pars), Agassiz. 



The body is fusiform, sometimes rather deep ; the scales rhomboidal, their overlapped 

 surface narrow, the exposed surface ornamented with striae and punctures, but some- 

 times nearly perfectly smooth. Rays of pectoral fin articulated; base of ventral short; 

 dorsal and anal large, triangular- acuminate ; dorsal situated behind the middle of the 

 back, so that the middle of its base is opposite the commencement of the anal; caudal 

 following closely on the anal, powerful, deeply-cleft, and inequilobate ; rays in all the 

 fins numerous, closely jointed, the joints scale-like. Suspensorium not quite so oblique 

 as in Palcconiscus, Elonichthys, and most other genera of the family, but more so than in 

 Amblypterus ; operculum large, oblong; suboperculum quadrate; branchiostegal rays or 

 plates numerous, with a median lozenge-shaped plate behind the symphysis of the 

 mandible, and the anterior one of each series broader than the rest. The jaws are 

 stout ; the teeth closely set, cylindro-conical, first inclined slightly inwards, then bent 



