166 TELEOSTOMES 
what seem to have been their primitive structural condi- 
tions. Their skeleton has become highly calcified, its ele- 
ments multiplying, fusing, and specializing. The notochord _ 
has practically disappeared, owing to the complete formation : 
of bony vertebra. The derm bones of the head, whichin 
ANCESTRAL 
_ TELeostome 
(TABLE IV) 
‘ 
' 
\ \N -- PALAEOZOIC M 
CROSSOPTERYGIAN 
AS PaLaeozoic 
\ PALAEONISCOID 
\\ ---- Mesozoic 
\ IN GANoID 
\ w---= MeESOzZ016 
| xe CATURIO 
\ XS 
\ 
‘\ \ 
STURGEON i i. 
Leriposteus —SiLUROID Fungnovene LOPHOBRANCH = SN 
‘POLYPTERUS Amia ACANTHOPTERYGIAN SYNGNAT 
Fig. r71 A. — The Phylogeny of the Teleostomes. 
the ancestral Ganoid were at the surface, enamel-coated,* | 
are now deep-seated in the head, resembling true cartilage __ 
* The enamel of Ganoid plates (ganoine) appears to be derived from the r: ‘ 
underlying bony tissue, not deposited by the overlying epidermis (enamel — 
organ). pa 
woes tj 
