No. 3.] CHEEK AND SNOUT OF AMIA CALVA. 431 
that, in Sagemehl’s opinion (No. 36, p. 98), they are all devel- 
oped in relation to certain definite underlying parts of the car- 
tilaginous cranium, with which, if they do not entirely displace 
and replace them, they may acquire so-called primary relations ; 
that certain of them may acquire relations to other cartilagi- 
nous parts than those to which they were primarily related 
(No. 17, p. 82); and that, in general, they acquire, because of 
their great persistence, independence and individuality, and 
their relations to each other, an ever increasing importance in 
the formation of the skull (No. 17, pp. 83, 84). 
The several single bones with which I am here concerned 
can now be considered. They have all been already described 
in Amia by Bridge (No. 7), and part of them by Sagemehl also 
(No. 35). The comparisons I shall attempt to make of the con- 
ditions found in Amia with those found in other animals are 
limited almost entirely to other fishes, to certain fossil reptiles, 
and toman. That the apparent homologies found between cer- 
tain of the bones, or combinations of bones, of Amia and other 
fishes and those of man cannot be considered as real until they 
have been traced through other classes is evident. They are, 
however, in many cases sufficiently striking to warrant their 
being presented. 
The nasal (VA, Pl. XX XIII, Fig. 1) of Amia is a slightly con- 
vex and irregularly oval bone which covers almost completely the 
relatively large and flat olfactory pit. Laterally it adjoins the 
antorbital bone; antero-mesially it overlaps the postero-lateral 
edge of the ethmoid; and posteriorly it overlaps two thin proc- 
esses of the frontal, which project forward, the one from the 
lateral edge of the bone, and the other from its mesial edge. 
Both of these processes arise from the deeper layers of the 
frontal, lie below the level of the outer surface of the rest of the 
bone, and have not, on their dorsal surfaces, the sculptured mark- 
ings peculiar to all the dermal bones of the outer surface of the 
skull of Amia. The lateral process rests directly upon the dor- 
sal surface of the preorbital ossification, and reaches or passes 
slightly beyond the dorso-posterior end of the antorbital bone, 
which bone will be later shown to be the probable homologue of 
the nasal process of the superior maxillary bone of man. As the 
