2G 



border lorm a conspicuous feature of the; fin. Individually they are not quite straight, but 

 have a slight sigmoid or double curve, and they taper to an obtuse point above. In the lower 

 part of the fin, where they arc most robust, their length is slightly over I'o mm., with a thick- 

 ness of about 0-3 mm. at their lower ends; they do not decrease much in size in the fin's distal 

 half. 



The anal fin is larger than the dorsal one, and what has been said regarding the structure 

 of the latter applies equally here. Its outline almost forms an equilateral triangle, with the 

 base slightly less than the anterior height, and with the posterior margin regularly and moder- 

 ately incurved. In one specimen in particular its proportions are well shown (figure 1, plate 

 VI) . In the type specimen, this fin, although admirably preserved with all details of ornaraen- 

 tation intact, does not exhibit the whole length of its base, as, posteriorly, there is a slight overlap 

 of the lower border of the caudal pedicle due to distortion. 



The pectoral fins are not well shown in most of the specimens seen. In one specimen, 

 however, represented in figure 1, plate VIII, the left one of the pair is fairly well preserved, 

 and from it we can judge of its proportions and relative size. In this specimen the fin is spread, 

 naturally and without distortion it would seem, and an idea of power is conveyed by its outline. 

 Its length, measured in a straight line from the base to the anterior distal end, is less than that 

 of the dorsal fin in the same specimen. The anterior or outer border sweeps round in a graceful 

 curve, and in this respect differs from the corresponding part of the dorsal and anal fins, which 

 is more nearly straight. The base is short and is contained about four times in the fin's length. 

 The inner margin is, in length, about equal to the base, but the posterior margin, when the fin 

 is spread, as in the specimen, equals four-fifths the total length of the fin. The rays have 

 about the same thickness as those of the dorsal and anal fins, and are similarly jointed and 

 sculptured, with this difference, that, proximally the first few anterior rays remain unarticu- 

 lated. The fulcra, continuous along the whole front border, do not differ from those of the 

 fins already described. 



The pelvic or ventral fins are relatively small, have a short base and seem to be long in pro- 

 portion to their width. Their fulcra are well developed. 



The caudal fin is preserved in a number of specimens in which its shape is clearly shown. 

 It is deeply forked. The long, acuminate upper lobe is formed to the extent of about one-half 

 its width by the body prolongation which reaches to its extreme tip. The lower lobe is shorter 

 and is apparently more rounded in outline at its extremity, not coming to such an acute 

 point behind. The fulcra of the lower lobe agree in size with those of the other fins. The fin 

 rays spring from the whole length of the lower surface of the body prolongation, beginning an- 

 teriorly below at a point not far removed from the posterior termination of the base of the 

 anal fin, and ending above at the distal extremity of the body prolongation. They are jointed 

 and sculptured as in the dorsal and anal fins. 



The scales are of moderate size, in the form of rhomboids on the flanks, with the usual 

 peg-and-sockot articulation, and with a considerable overlap. On the flank, half way between 

 the dorsal fin and the head, their height, or breadth, is three-fourths of their length, plate V, 



