180 
PKOr. D. M. S. WATSON AND MR. E. L. GILL ON THE 
among the scattered but practically complete remains oi: a head of Sagenodus ; 
the other two are detached. It is a bone of graceful form, delicately striated 
on one face in lines converging towards a small tubercle near the blunt end. 
The other face is smooth. Fig. 16, B^ p. 181, shows the size of the bone in 
relation to the lower jaw and the manner in which we suggest that it fitted 
Fig. 14. 
Saqetiodus sp. Right angular and " dentary " in natural association, x If. 
in the gular space. Compared with the extensive gular apparatus of 
Dipterus, described later, it is meagre, but it is much what might be looked 
for in a fish which in so many respects is a transitional form between the 
early Dipnoi and Ceratodics. 
Fig. 15. 
Sagenodus. A, B, C, outer surface of three " dentaries,'' x about | ; D, inner 
surface of a left "dentary," oblique view sbowinpr tbe character 
of the symphysis a.nd of the hinder border. 
The Ojjercidar Bones. 
Next to the teeth, the operculum is probably the best-known of the remains 
of Sagenodm. In proportion to the head as a whole, it is remnrkable for 
its size and massiveness. Its manner of attachment to the skull has been 
described already (p. 169). In common with the other bones, it varies gre;itly 
