240 
Pachycormus in the Moore Collection. No example is perfect, 
but nearly every specimen exhibits some point of importance. 
Several specimens display the remarkable median ridge at the 
top of the back of the skull, which meets the high and arched 
trunk of the fish; and one detached example shows that the 
greater part of this ridge is formed by the frontal bones, the 
parietals being small and only meeting in the middle line for a 
very short space. This and other skulls are filled with calc-spar 
in such a manner as to suggest that there was a good deal of 
unossified cartilage in the cranium. One specimen, however, 
proves that the basioccipital, supraoccipital, exoccipital, and a 
hinder pair of otic elements were well ossified ; though there is a 
gap between the supraoccipital, as preserved, and the cranial roof. 
The exoccipitals do not meet above the foramen magnum. 
The fan-shaped hemal spine at the base of the tail is also seen 
in several specimens, and distinctly shown to represent only a 
single segment of the vertebral column. A detached example of 
the tail exhibits three radiating grooves in this expanded bone; 
but they appear to be merely superficial, and probably do not 
imply its compound character. 
The other features are so obvious in most specimens that no 
further reference need be made to them. It only remains to note 
that owing to the original shape of the fish, the fossils exhibit an 
extraordinary variety of contortion and dislocation, and it is diffi- 
cult to ascertain their proportions. Without more detailed study 
and comparison than has hitherto been bestowed upon them, it is 
thus impossible to determine how many species are represented. 
In fact, the naming of the species of Pachycormus is still almost 
chaotic. The Moore Collection probably includes the typical 
Pachycormus acutirostris, the smaller P. curtus, and a new small- 
scaled species. 
SAUROSTOMUS Ok PACHYCORMUS. 
The gem of this collection of Pachycormide, however, is a large 
fish about a metre in length with wide skull and comparatively 
