212 Dr Hiszert on the Limestone of Burdiehouse, 
mens of them attaining the diameter of five inches ; but, in pro- 
portion to their great magnitude, they appear to grow thinner. 
It is supposed by M. Acasstz, that these relics will meet with 
an explanation in the Plate of scales given of the Lepidosteus in 
the first volume of his “ Recherches sur les Poissons Fossiles ;” 
and that they are referable to such dorsal scales as are to be found 
at the top of the long series which traverse the Plate, given by 
him in Vol. ii, Tab. B. 
With these observations, the communication with which I 
have been favoured by M. Acassiz relative to the sauroid re- 
mains of Burdiehouse, is concluded. Some few additional obser- 
vations from the same eminent naturalist, (See the Edinburgh 
New Philosophical Journal for January 1835), on the compara- 
tive character of the large sauroid fish of early and more recent 
formations, will properly close the present inquiry. 
He states, that it is in the deposits below the lias that we 
begin to find the largest of those enormous sauroid fish, “ the 
osteology of which recalls in many respects the skeletons of 
saurians, both by the closer sutures of the bones of the skull, by 
their large conical teeth striated longitudinally, and by the man- 
ner in which the spinous processes are articulated with the body 
of the vertebra, and the ribs at the extremity of the spinous 
processes.” 
It is likewise remarked, that “ we do not find fish decidedly car- 
nivorous before the carboniferous series ; that is to say, provided 
with large conical and pointed teeth. The other fish of the se- 
condary series before the chalk appear to have been omnivorous ; 
their teeth being either rounded, or in obtuse cones like a brush.” 
I cannot sum up this portion of the investigation, without 
adverting to the geological importance of selecting for purposes 
of comparison and analogy, of which the Lepidosteus affords a 
splendid example, animals subsisting in recent times, which may 
