144 TELEOSTOMES 
Such in outline are 
the essential structures 
ofa Teleost. They may 
now be briefly con- 
trasted with the more 
important characters of 
the Ganoids. 
In skeletal structures 
the Perch (Fig. 146) 
may be strikingly con- 
trasted with the most 
nearly ancestral form 
of Ganoid (Fig. 147). 
In this, Polypterus (p. 
148), the skeleton re- 
tains a_ semi-calcified 
condition. Its verte- 
DSG. Dermal scales 
O. Operculum. P. Pelvic 
SF. Jugular bones (scales). LZ. Longitu- 
HA, Heemal arches. 
NA, Neural arch. MS. Neural spine, 
R’. Rib (transverse process). AZ. Radial and basal fin supports. S. 
B. Basal fin supports. D. Dermal fin supports. DN. Dentary. DS. 
SP’. Splenial. 
xX}. This figure should be compared with Fig. 146. 
DS’. Secondary dermal spines (radials, in part) of dorsal fin. 
¢“@s bral centra are practi- 
Oo g 
g are g cally separate from the 
Sp : £q arches; its ribs, X, are 
SS 3% oa , 
: ; 3 <f equivalent to the trans- 
s< gee & = verse processes ; its ac- 
Sau R : 
2s yj d r cessory ribs, AR, to 
& uo} . 
satsiga2 the “ribs” of Teleosts. 
SESES A — nn 
6-2 50°. Thecartilaginousbrain 
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egue E %@ tained; the membrane, _ 
3 3 5% £8 or dermal bones, of the | 
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e#22253 PO, O, are clearly 
Se GPaty we ; 
i ga 32 scale-like, with an 
&®*E2224 enamelled surface, sim- 
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ilar in character to 
