440 Br. Traquair — New Species of Palceoniscidce. 



II. — New Paljeoniscid^: from the English Coal-measures. 

 By E. H. Traquair, M.D., F.R.S., F.G.S. 

 Elonichthys Aitkeni, sp. nov., Traquair. 



LENGTH, 6 to 7 inches, shape fusiform. Cranial roof bones sculp- 

 tured with undulating ridges passing at times into elongated 

 tubercles. Mandible sculptured externally with slightly undulating 

 longitudinal ridges, which run tolerably parallel with the upper and 

 lower margins of the jaw; dentary margin finely tuberculated. 

 Maxilla of the usual form, its dentary margin likewise finely tuber- 

 culated, the rest of the surface covered with undulating ridges. 

 Scales of moderate size ; those of the front of the flank are higher 

 than broad; posteriorly they become more oblique and equilateral, 

 while towards the dorsal and ventral margins they become rather 

 lower than they are broad. Their ornament consists of sharp strongly- 

 marked ridges, nearly straight and parallel, and only occasionally 

 bifurcating or intercalated. On the scales of the anterior part of the 

 flank these ridges run rather diagonally over the surface of the 

 scale from above downwards and backwards, but over the greater 

 part of the body they are parallel with the upper and lower margins of 

 the scale, and seldom does any greater obliquity of the ridges in the 

 anterior and lower part -of the scale give any indication of the 

 diagonal division of the pattern which is so common in striated scales 

 in the family Palasoniscidse. Posteriorly, a peculiar and highly- 

 ornamental character is given to the squamation by the fact that 

 the lowermost ridge, uniting or not with the one next above it, is of 

 unusual breadth, and stands prominently out. On the V-shaped 

 ridge-scales of the caudal body-prolongation, the ornament becomes 

 speedily obsolete, and the small lozenge-shaped lateral scales are 

 at most marked by only one or two slight longitudinal furrows. 



The length of the pectoral fin is about two-thirds that of the 

 head, its principal rays are unarticulated for about one-third of their 

 length. The ventrals are badly preserved, but their position seems 

 to be intermediate between the pectorals and the anal. The dorsal 

 is situated opposite the interval between the ventrals and the anal ; 

 both dorsal and anal fins are pretty large, and of the usual triangular 

 acuminate shape ; their rays are delicate and slender, distantly arti- 

 culated, ganoid and smooth, save that now and then a single longi- 

 tudinal furrow is seen especially just before bifurcation sets in. The 

 caudal is large and deeply cleft ; the articulations of the rays of the 

 lower lobe are a little closer than those of the dorsal ; in the upper 

 lobe the joints become so short as to look nearly square-shaped. 



Bemarks. — Though hitherto undescribed, this fine species is 

 pretty well known to collectors in the West of England, and cannot 

 be confounded with any other. I have named it after the late 

 Mr. John Aitken, of Bacup, Lancashire, who lent me the beautiful 

 specimen, of which a figure will shortly appear in my memoir on 

 Carboniferous fishes in course of publication by the PalEeontogra- 

 phical Society. 



Geological Position and Localities. — Lower Coal-measures. Copy 



