﻿5S GANOID FISHES OF THE CARBONIFEROUS FORMATION. 



which belonged to the late Professor Jameson, and was also referred to by Agassiz, must 

 have attained a length of nearly eight inches had it been perfect ; unfortunately, how- 

 ever, its head and a portion of the front of the body are deficient. The largest specimen, 

 however, of Elonichthys striolatus which I have seen is one belonging to the Museum of 

 the New College, Edinburgh ; both head and tail are wanting, but judging from the 

 depth of the body and the size of the fins, one of which, the dorsal, is represented 

 of the natural size in PI. VII, fig. 5, it could not have originally measured less than 

 nine inches in length. 



Very little can be made out concerning the osteology of the head, the bones of which 

 are, as is unfortunately the case with most of the smaller fishes preserved in hard 

 limestones or bedded ironstones of the Carboniferous Period, crushed into a nearly 

 homogeneous mass. The gape is, however, seen to be very wide, the suspensorium 

 very oblique, the lower jaw stout and striated with fine oblique ridges. In the specimen 

 represented in PI. VII, fig. 7, the lower jaw of the right side is seen from within, with 

 obvious remains of branchiostegal rays below it ; of the latter, the median lozenge- 

 shaped plate behind the symphysis is conspicuous. Here the dentary margin 

 may be observed to be set with numerous teeth of different sizes, the largest of 

 which measures inch in length. All these teeth are conical, sharp, and incurved, 

 with enamel cap ; the surface is polished and smooth under an ordinary lens. They 

 are not at all arranged " en brosse," and the larger ones are, in proportion to the size of 

 the jaw, just as large as in such a form as Acrolepis. Indications of similar teeth, as 

 well as of smaller ones outside them, are also seen in the specimen represented in 

 PI. VII, fig. 4. 



The scales are of moderate size, being larger on the front part of the flank, where the 

 upper margin is slightly concave, than the lower convex ; they become gradually smaller 

 and more obliquely rhomboidal towards the tail. The keel on the under surface is well 

 marked (fig. 13), and terminates above just in front of the origin of the rather prominent 

 articular spine of the upper margin, which with the corresponding socket above the 

 lower margin becomes less marked, and finally disappears towards the commencement of 

 the anal fin ; the keel, however, endures as far as the scales of the tail-pedicle, and is 

 even more prominent in the posterior part of the fish (fig. 15). The external surface of the 

 scale has the covered portion extremely narrow, the exposed area is in the anterior part of 

 the fish (PI. VII, fig. 12), marked with very delicate furrows, whose direction is first 

 obliquely downwards and backwards, then passing more or less directly across the scale, 

 and tending posteriorly to pass into short streaks and punctures ; some of the uppermost 

 of these furrows are observed to run nearly parallel with the upper margin. In front, 

 where these furrows are most pronounced and closer together, an appearance is pro- 

 duced as of delicate bifurcating ridges between them, and in some of the most 

 anteriorly placed scales (fig. 11) these ridges extend, indeed, over nearly the entire 

 surface. As we proceed backwards along the body the appearance of striation becomes 



