No.3] CHEEK AND SNOUT OF AMIA CALVA. — 455 
relation of that bone to the septomaxillary and its turned-down 
lateral edge suggest the possibility of its bemg the homologue 
of the posterior process of the premaxillary of Amiz, although 
in all other respects it much more resembles the ethmoid. In 
certain of the Cyprimidae the bone seems to have fused with the 
preorbital ossification instead of with the premaxillary, as the 
conditions described by Sagemehl (No. 37, p. 566) im the genera 
Labeo and Osteochilus, in particular, strongly indicate. In the 
frog the bone may be represented in the septomaxillary. If it 
exists in man, it must certainly have its homologue in that part 
of the ethmoid that binds the lateral masses of the bone to the 
vertical plate; that is, m some part of the cribiform plate. 
The fact that the nasal sac is, in selachians (No. 47, p. 106) 
and im certain cyprinoids (No. 37, p. 568), separated from the 
cranial cavity by 2 membranous lamina cribrosa strongly sup 
ports this supposition. If this be so, the anterior end of the 
bone in Amia is certainly the homologue of the posterior end 
of the plate in man; and if the nasal apertures of animals, one 
or both, lie primarily on the ventral surface of the head, as 
Wiedersheim states (No. 46, p. 304), the position of the bone 
in Amia and Gymnarchus must necessarily be a secondary one. 
Whether the internal nasal aperture of man is of secondary 
origin, as Wiedersheim states, or is the homologue of one of 
the external apertures of Amia, would make no difference in 
this conclusion. The crista galli of man would, m either case, 
seem to be represented m Amia by the hind end of the cart? 
laginous wall that separates the olfactory canals and looks back- 
ward into the anterior extension of the cranial cavity. 
If these several homologies are correct, the anterior nasal 
spine of the superior maxillary bone of man is naturally the 
ascending process of the premaxillary bone of teleosts and uro- 
deles—the separate ethmoid bone of Amia —and the nasal 
not also of those of Reptilia. If this process of Amm is here correctly idemtiiied 
the vomers of Ami must be either the prepelatine elements of Sutton’s desop 
tions, or these palatal pltes of the premanillaries of Gomphognathss that are said 
by Broom (Ja. aé#., p. 278) to meet in the middle Ime behind the median choana 
The “apparently hitherto undescribed nasal dicor bome ~ would then seem certainly 
to be the septomanxiilary cf Amia and the peresphencad of that fish the womer of 
mammals, 25 Sutton states 
