Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/676

576 is associated with it in the same beds. The only entire specimen I have seen is 11$1⁄2$ inches in length; it is most unfortunately crushed on its back. It displays, however, the right pectoral and ventral fins; and the former, unlike the pectoral of Pygopterus, has its principal rays articulated throughout; the ventral is of moderate size. The median fins are large; the dorsal is not shown in any of the specimens belonging to the Edinburgh Museum; but in Dr. Hibbert's figure it is seen to resemble the anal, and is evidently placed nearly opposite the interval between that fin and the ventrals, though the latter are not shown in the figure. The anal, however, is well shown in one specimen; it is large, triangular, and acuminate, and is closely followed by the caudal, which is very powerful. The fin-rays are externally ganoid and finely. striated; their transverse articulations are very close; the fulcra are closely set, and minute for the size of the fish. The scales of the body are proportionally small. Those of the front part of the body are apparently nearly equilateral; but posteriorly, and more especially towards the ventral margin, their form is low and narrow. Their anterior covered area is very narrow; the posterior margin is very finely denticulated; the exposed area is covered with a delicate yet sharply defined ornamentation, consisting of fine subparallel ridges, which pass from before backwards across the scale, in a gently sigmoid direction, tending to become intermixed with punctures posteriorly, especially above the diagonal between the two acute angles of the scale. Towards the tail the ridges become less marked on the posterior part of the scale, giving way to the thickly dotted punctures, till on the caudal body- prolongation the former, after lingering at the anterior margin, altogether disappear, and punctures alone remain.

Very little can be made out concerning the bones of the head; however, in the above-mentioned entire specimen the lower jaw is seen to be very stout, and ornamented externally with fine, sharp, closely set, wavy, branching, anastomosing, and interrupted ridges, running in a longitudinal direction. The laniary teeth are very strong, incurved and smooth, with apical enamel-cap; similar teeth are seen on the maxilla, the dental margin of which is finely tuberculated.

Imperfect as the above-described specimens are, the affinities of the fish which they represent are clear and unmistakable, and forbid its being retained any longer as a "Pygopterus." On the other hand, though attaining a larger size, the resemblances which it bears to Elonichthys striolatus, in the form, structure, and position of the fins, and in the nature of the scale-ornament, are so great that it is impossible to include them in different genera, though specifically they are at once distinguishable.

I have already stated that the original of "Pygopterus" Jamesoni seems to be lost, and that, as no figure or description of it exists,