50 Dr. A. Smith Woodward—On Saurostomus esocinus. 
angular bone is relatively small, and the dentary is as originally 
described by Agassiz. The lower teeth of the spaced series are 
slightly larger than those of the upper jaw, but are similarly flanked . 
outside by clustered minute teeth. All the teeth are conical, a little 
incurved at the apex, covered with smooth enamel, and: vertically 
fluted at the base. The preoperculum, operculum, and suboperculum 
are vaguely seen, of the characteristic shape. Behind the large gular 
late there are also traces of the branchiostegal rays. 
The trunk is distorted as usual, especially just in front of the 
dorsal and anal fins, which are thus separated a little from their 
supports. The vacant space for the notochord is widened by this 
distortion, but most of the arches above and below are well preserved. 
The total number of vertebral arches is about 110, of which 50 may 
be assigned to the abdominal region. The ribs are comparatively 
short and slender, while the neural arches of the abdominal region 
bear gently curved spines, each forming an irregular node at its 
fused lower end and tending to slight expansion at its upper or distal 
end. In the caudal region the simple neural and hemal arches are 
nearly symmetrical above and below the notochordal space, and 
sharply inclined backwards. Within the base of the tail six or 
seven hemals become relatively stout, and the last hemal forms the 
fan-shaped bone which is so characteristic of the Pachycormide. 
In the pectoral arch the two supraclavicles are well seen, relatively 
large, long and narrow, straight, and of conspicuously fibrous texture. 
The clavicle is obscured, but behind it there are traces of the usual 
thin and large postclavicular scales. The right pectoral fin is 
specially well preserved, with at least twenty rays, which do not 
appear to be transversely articulated but become very finely divided 
distally. The fourth or fifth and longest ray is gently curved and 
much longer than the others, which rapidly shorten backwards.’ 
There is no trace of pelvic fins. The supports of the dorsal and anal 
fins, which are well preserved though displaced, are remarkable for 
their great length. Not less than twenty-five or twenty-six of these 
supports are shown in each fin, all expanded at the end for articulation 
with the fin-rays. The dorsal fin must have been almost completely 
in advance of the anal, and the fragmentary remains show that it was 
elevated in front, comparatively low behind. The anal fin is 
altogether less elevated, and the articulations of its rays are shown to 
have been distant. The rays of the powerful forked caudal fin are 
also articulated only at distant intervals, but are very finely sub- 
divided distally. 
Nearly all the scales have been removed from the fossil, but a 
scattered patch behind the dorsal fin shows that they are small and 
thin, with some traces of a very fine tuberculation. There are vague 
remains of the enlarged scale at the origin of the anal fin. Indications 
of digested food are also seen in the abdominal region. 
The most interesting feature of this new specimen of Sawrostomus 
is the remarkable elongation of the anterior pectoral fin-ray, which 
1 The pectoral fin from Whitby figured in Proc. Yorks. Geol. and Polyt. 
Soc., vol. xiii, pl. xx, fig. 2, 1896, thus seems to belong to Pachycormus, not to 
Saurostomus. 
