576 RAMSAT H. TRA0JJA1R ON AMBLYPTERUS, 



is associated with it in the same beds *. The only entire specimen 

 I have seen is 11| 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. Hib- 

 bert'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 articu- 

 lations 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 ex- 

 posed area is covered with a delicate yet sharply defined ornamen- 

 tation, 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 tuber- 

 culated. 



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 Eloniclithys 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, 



* These species are described in the first part of my monograph on the 

 British Carboniferous Ganoids, in the Memoirs of the Paleontographical Society 

 for 1877, plates 3-7. 



