94 On a new Leptolepid Fish from the Weald Cla\j. 



in tlie liindcv part of tlio caudal region. Thoy are well ossified 

 and their primitive double-cone is strengtliened by secondary 

 bone arranged in fine, close, longitudinal ridges (fig. 2). 

 The ribs are stout, apparently borne on very short transverse 

 ])rocesses, and clearly extending to the ventral border of the 

 fisli. The fixed neural and hsemal arclies in the caudal 

 region are also very stout and gently arched. The hinder 

 extremity of the vertebral column turns only slightly upwards, 

 and its ha3mal arches are somewhat expanded without fusion 

 into plates. The intermuscular bones are almost completely 

 obscured by the scales in the fossil, but there are traces of 

 llieni above the vertebral column in the abdominal region, 

 and both above and below this column in the caudal region. 

 IMie post-temporal {jpt.) is a thick plate, almost triangular in 

 shajie, and the supraclavicle {scl.) is a deep and narrow bone. 

 The clavicle (c/.), as shown in impression, is expanded into a 

 large smooth plate above the pectoral fin, which is inserted 

 close to the ventral border. When adpressed to the trunk 

 this fin extends halfway to the insertion of the pelvic fins ; 

 its rays have a very long and stiff base, but are finely divided 

 and articulated at the extremity. The pelvic fins {ph.) are 

 smaller than the pectorals, though similar in character, and 

 inserted midway between the pectorals and the anal. The 

 dorsal fin {d.) arises well in front of the middle point between 

 the occiput and the caudal fin, somewhat in advance of the 

 insertion of the pelvic fins. It comprises eighteen to twenty 

 rays, of which the three foremost are closely pressed together, 

 undivided, and gradually increase in length. The length of 

 the fourth or longest ray much exceeds half the depth of the 

 trunk at its insertion, and, like the following rays, is finely 

 divided and articulated distally. The anal fin [a.) resembles 

 the dorsal in character, but is much smaller and comprises 

 only thirteen or fourteen rays. It is far behind the dorsal, 

 and its origin is much nearer to that of the caudal than to 

 the insertion of the pelvic fins. The remains of the caudal 

 fin-rays (c.) show that they were comparatively stout. There 

 are no fulcra on any of the fins. The scales are relatively 

 large, cycloid, and smooth, occasionally with feeble traces 

 of a slight radiating pectination at the hinder border, but 

 usually exhibiting structural lines, including wavy concentric 

 markings. They are scarcely displaced in the fossil, and are 

 seen to be deeply overlapping, with the exposed area narrow 

 and deep. The '^ lateral line " is scarcely traceable, but 

 seems to produce a slight depression along some scales in a 

 series above the vertebral column. 



So far as the skeleton is preserved there is nothing in the 



