52 
The Ohio Naturalist. 
[Vol. IV, No. 3 
COMPARATIVE CHART OF THE VERTEBRATE 
SKULL.* 
Chaki.ks S. Mkad. 
In compiling the following chart, an attempt has been made to 
show the histor}" of the cranial bones in the different classes of 
\-ertebrates. To make it general as well as specific from one to 
four types are given under each class, and where possible, an 
unspecialized and a highly specialized form have been taken. As 
a rule, the same bone occurs in the different classes of vertebrates, 
but it may fail to develop, as in the Amphibians, or several bones 
may fuse to form larger elements, as in the Mammals, and it is 
the purpose of this chart to show these irregularities. 
In the higher types, especially the birds, there is a great ten- 
dency for bones that are separate in the immature stages to fuse 
in the adult, the sutures being obliterated. In Lacerta and the 
Amphibia many elements that are indicated as bones remain carti- 
laginous. Where two or more bones in one tj-pe fuse to form 
one bone in another type the line between them has been omitted. 
In the Urodeles, Ophidians, and Chelonians no particular type 
has been taken. 
Different authors have used different names for the same bone 
in the same class or different classes, or the same name maj' be 
used for as many as four different bones. Below is given a list of 
S5’nonyms ; 
Jugal, malar, zygoma, zj’gomatic. 
Ouadrato-jugal, zj-gomatic. 
Squamosal, supratemporal of Ophidians. 
Supra-angular, suraugular. 
Coroiioid, coronary. 
Lacr3'mal , .supraorbital . 
Sphenotic, postfrontal. 
Prootic, ])etro.sal. 
Periotic, petrosal of Mammals. 
Epipteyvgoid, columella. 
Transver.se, ectopterx'goid, transversum, transpalatine. 
Pterj'goid, ectopter\-goid. 
IMesopter\’goid, eutopter\'goid. 
Mesethmoid, ethmoid, supra -ethmoid, median ethmoid. 
Ectoethmoid, ectethmoid, parethmoid, lateral ethmoid. 
Turbinal, ectoethmoid. 
Maxilla, maxillarj', .supermaxilla, superior maxilla. 
Premaxilla, intermaxilla, anterior inaxillarN-, incisive. 
' From the Zoological laboratory of the Ohio State University. 
