AFFINITIES OF CHIMAZROIDS III 
that it occurs abundantly in the shallow waters of Van- 
couver; it is there well known as the “rat fish,” and may 
often be seen in the neighbourhood of the docks, swim- 
ming slowly at the surface. 
The shape of the body of Chimzra seems in some re- 
gards to have diverged from the more shark-like form of 
Callorhynchus. Its organs have become concentrated in 
the pectoral region, and ‘the disturbance in the curve 
normals of the fish seems to have caused the shortening of 
the snout, and the sudden dwindling of the hinder trunk 
region; the tail, with its thread-like terminal, the opis- 
thure (Fig. 120), is accordingly to be looked upon as de- 
Fig. 120.— Chimera monstrosa, 3. Juv. X about 3. (After L. AGassiZ.) 
The anterior ventral clasper is noted at X; the tail terminates in a thread-like 
opisthure, 
generate. In the anterior region, however, a number of 
what seem to be primitive characters have been retained; 
_ the mucous canals are groove-like ; and the dental plates 
_ (Figs. 109, 109 A) exhibit a series of tritoral areas. 
Affinities 
_ All that is known of Chimzeroids, living or fossil, gives 
_ but little definite knowledge of the kinships or evolution 
of the group. Their shark-like structures cannot be shown 
to have taken their origin from shark-like conditions. 
_ Thus the dental plates even of the most ancient forms 
_ do not suggest their derivation from shagreen cusps; the 
