WOODWARD : FOSSIL FISHES OF THE UPPER LIAS OF WHITBy. 159 
also evidently indistinguishable, have subsequently been named 
Fachycormas giganteus and F. bollensis, while an identical detached 
head from the Upper Lias of Yonne, France, is described and figured by 
Sauvage (loc. cit.) under the name of Cat u?' us gigas. Of all the names 
mentioned, that of Saurostomus esocinus is the earliest, and this must 
therefore be used for the Whitby fish, unless (as some authors have 
done) we change it to Fachycormus esocinus. The latter, however, is 
probably an undesirable emendation ; for it will be noticed that the 
roof of the skull is quite flat, not raised into a median ridge at the 
back, while its constituent bones are less completely fused together 
than in the typical Fachycormus. We may also add that the *" lateral 
line" on the tail in a fine specimen from Ilminster, in the Moore 
Collection, Bath, is supported by a row of somewhat enlarged scales, 
such as have never been observed in any undoubted species of Fachy- 
cormus. 
The specimens in the British Museum, labelled Fachycormus 
latirostris by Agassiz, comprise (i.) an imperfect head with opercular 
apparatus, (ii.) a very imperfect vertically crushed specimen of the 
same with its pectoral fins, and (iii.) a detached pectoral fin, all from 
the Enniskillen Collection. A fractured nodule with remains of the 
head and pectoral fin, in the Egerton Collection, is also similarly 
labelled by the late Sir P. de M. Grey Egerton. 
The first specimen (No. P.3708) is important, and is shown of 
two-thirds the natural size in pi. xx., fig. 1. This represents the 
right side of the fossil completed by the addition of the operculum 
from the opposite side. Fig. la, of the natural size, shows part of 
the anterior dentition which may be premaxillary, though the bone is 
obscured by matrix. The greater part ot the fossil is much obscured 
by intractable matrix. In front of a transverse fracture across the 
anterior frontal region, the snout is crushed downwards ; but the 
remarkably obtuse appearance (r.) in side view may be misleading, 
only matrix being exposed here. The roof of the skull is nearly flat, 
with a slight median depression, and no elevation in the occipital 
region. The small parietals can be distinguished meeting in the 
middle line, ornamented with very fine tubercles and rugae disposed 
along the radiating lines of growth. An impression of the squamosal 
D 
