VIII PECTORAL AND PELVIC GIRDLES 241 
Crossopterygil and Chondrostei an infraclavicle or clavicle proper, 
while one or two “ post-clavicles” may be present in relation with 
the hinder margin of the cleithrum. The infraclavicles, or in 
their absence the cleithra (e.g. Holostei and most Teleostei), 
usually meet in a median ventral symphysis, so that the secondary 
girdle tends to acquire the characteristic hoop-lke arrangement 
of its parts which has-been lost in the primary girdle. With 
the development of a bony secondary girdle, the primary girdle 
(scapula and coracoid) becomes much reduced, and, as a rule, 
does little more than connect the fins with the cleithra. 
The secondary girdle acquires a dorsal connexion with the skull 
on each side by means of the 
post-temporal bone, which is 
attached below to the supra- 
clavicle and above to the periotic 
capsule. In the Chondrostei 
and the Dipnoi the primary 
girdle retains its primitive carti- 
laginous condition, but in the 
Crossopteryegii, Holostei, and in 
all Teleosts it 1s ossified as dis- 
tinct scapulae and coracoids. To 
these may be added in some 
Teleosts a mesocoracoid formed 
by a separate ossification of the 
coracoid cartilage (Hig. 143) Fig. 144.—Ventral view of the pelvie girdle 
With the possible exception of Protopterus. a, Prepubie process ; 
of small paired or median carti- fetes! proms fr the ns agate 
lages inserted between the inner fin muscles; HH, skeleton of the 
extremities of the basipterygia ee eee ae at aa 
in Polypterus and a few other 
Teleostomi, the pelvic girdle is absent in all the existing members 
of this group, having either become completely suppressed, or 
remaining unseparated from the basipterygia of the pelvic fins. 
In the Dipnoi (Fig. 144) there is a true pelvic girdle which has 
some points of resemblance to that of certain of the caudate Am- 
phibia. It is represented by a median, lozenge-shape, cartilaginous 
1 It is more probable that in most existing Teleostomi the pelvic girdle has 
undergone complete suppression, in which case these cartilages are vestiges and 
not rudiments. 
2 See, however, Goodrich, Quart. Journ. Mier. Sci. xlv. 1901, p. 311. 
VOL. VII R 
