No. 3.] CHEEK AND SNOUT OF AMIA CALVA. 445 
orbital canal line of the lateral-line organs of Amia, and fused, 
in Polypterus, with the maxillary and supramaxillary bones, the 
zygomatic arch of man must be this chain of sense-organ bones 
fused, in part, and in part articulated with each other and with 
the proximal part of the preoperculum, and the latter bone 
fused with the squamosal. The persistence of this chain of 
bones, and the disappearance of the long preopercular connec- 
tion between the squamosal and the lower jaw, so characteristic 
of fishes, would be naturally associated with the disappearance 
of a suspensorial apparatus. 
The zygomatic process of the temporal bone of man is, then, a 
part of the preoperculum of fishes ; and the malar bone is certain 
of the infraorbital bones, fused, perhaps, with other elements, 
such as the supramaxillary, or a post-suborbital element not 
found in Amia. The occasional division of the malar bone into 
two parts by a horizontal suture (No. 32, Vols Padapcy9) 
may be due to this origin of the bone in connection with two 
lines of sense organs, or, possibly, to the fusion of bones of sense- 
organ origin with others developed in connection with teeth- 
bearing plates. The abnormal formation, in the skull described 
by Torok (No. 43), of a distinct suborbital arch, consisting of 
a process of the malar bone and two separate and independent 
bones, is apparently due to a still further separation of these 
same two elements.! 
1 Maggi, in a recent publication (“ Autres résultats de recherches morpholo- 
giques sur des os craniens et cranio-faciaux et sur des fontanelles de homme et 
d’autres mammiféres,” Arch. /tal. de Biol., Tome XXX, Fasc. II, 27 Dec., 1898), 
makes the following statement: ‘Le centre d’ossification de la squame propre- 
ment dite ou de la portion squameuse du temporal qui se manifeste un peu au- 
dessus de la place correspondant 4 la base de son apophyse zygomatique, est 
homologue au pré-operculaire du Polypterus ; le centre d’ossification de ’apophyse 
zygomatique du temporal est homologue au sub-operculaire du Polypterus ; le 
centre d’ossification de l’épitympanique de Rambaud et Renault, ou serriale d’Et. 
Geoffroy Saint-Hilaire, est homologue 4 operculaire du Polypterus.” The homo- 
logue here proposed for the preoperculum of Polypterus differs radically from 
that proposed by me, in that Maggi finds it in a part of the squamosal, at the base 
of the zygomatic process, instead of in that process itself. In the same publica- 
tion Maggi states that the postorbital bones are found in the human infant as 
“noyaux d’ossification . . . places sur le cété antérieur de l’extremité triangulaire 
de la grande aile du sphénoide.” According to my determination they would be 
found in the frontal process of the malar bone. As Maggi himself says (‘“ Post- 
frontale nei Mammiferi,” Rendic R. Istit. Lomb. Sc. Lette. (2) V. 30, Fasc. 9) 
