WOODWARD : FOSSIL FISHES OF THE UPPER LIAS OF WHITBY. 163 
been only superficially calcified. The haemal arches at the base of 
the tail are comparatively stout, and there are traces of the great 
triangularly-expanded hoemal already noted by Quenstedt* in 
specimens of Pachycormus from Boll. So far as they can be observed, 
the scales are smooth and of tolerably uniform size, some longer than 
deep near the ventral border. There is also a fragment of the 
enlarged median scale at the origin of the anal fin. 
A specimen preserved in shale, in some respects more satisfactory, 
is shown of the natural size in pi. xxi., fig. 1. The general propor- 
tions of the fish are here probably well indicated, but the head and 
pectoral region are a little crushed upwards, so that the right mandi- 
bular ramus and base of the pectoral fin are exhibited considerably 
above those of the left side. The head and opercular apparatus, 
however, are too imperfect for detailed description. The axial 
skeleton of the trunk is obscured by the scales of the abdominal 
region, but a few delicate ribs are seen in its hinder portion. The 
remarkably short, much inclined neural and haemal arches in the 
caudal region exhibit the internal hollow filled with spar, while those 
at the base of the caudal fin are thickened as usual, and the axis is 
disturbed just in front of the latter. The long and narrow pectoral 
fin is well preserved on the left side, though with imperfect anterior 
border ; it exhibits about twenty-one rays, mostly broad, all divided 
and articulated at the distal end. There is no trace of pelvic fins. 
The dorsal fin is somewhat crushed and imperfect distally. It arises 
slightly in advance of the middle point between the occiput and the 
base of the caudal fin, and is borne by at least thirty supports, which 
are more or less disturbed and fractured, and show an internal axis 
of spar. The anal fin is slightly more than twice as distant from the 
pectorals as from the caudal, and appears to display its true form 
with the anterior acumination, though the rays are obscured in the 
middle by a longitudinal streak of matrix. Its supports are about 
twenty-five in number, each with an internal core of spar ; and those 
situated anteriorly are the longest, while those in the hinder half of 
the fin can be observed to correspond exactly in number with the 
rays they support. The caudal fin is apparently complete, though 
* F. A. Quenstedt, Der Jura, p. 236, pi. xxxii., figs. 3, 4. 
