PO en eee es ee ae ee 
a ae ieee 
* 
RIBS, AND SCALES OF CTENODUS. 63 
thinks that “ the a fot far cw the noes be nar = in C. elegans, 
a e tail fin real and 
which any trace of a fin or tail 8 a oak detected, rg as it is 
acknowledged to be much injured, it will be advisable to leave 
this portion of the fish’s struc mieegey to be determined by the in- 
vestigations of future 1 Fs 
T have now entered & ag detail into = oe fossil remains 
a 
one eag into the igen: of the upper portion of the cranium 
 3E fits = Senet tise bones that are 
todus in its fundasiental construction, so far as it is known, even 
in those parts that yet may be considered somewhat doubtful, 
such as the scales. When we take into consideration the distant 
period in which Céenodus lived we can hardly expect that the 
type could — been handed down to the present time, countless 
, Without a few alterations of structure due to 
probably sufficient. Then when this fish made its way ou 
the waters on to the dry lands or upon the swampy coasts, its iif 
would be in danger from the huge Batrathians that. swarmed ; 
eoracoid for greater muscul tachment. Finally, the much 
te of “Ct s would necessarily require a larger an 
r surface for the attachment, of the powerful muscles that 
Por some of the species ‘were ack over six feet in length. 
With none of these dangers has the modern fish had to contend ; 
therefore, in the great battle of the “survival of the fittest” 
less strength has been required of it, and consequently in the 
process of time an alteration would take place in the skeleton, 
to render it com compatible with e: siveimetion neces. 
