17 
the other case, however, in which the terms sphenotic and 
post-frontal are synonyms, we cannot adopt the same plan, 
since the term post-frontal cannot be correctly applied to 
a membrane bone ?n Fishes. We must hence distinguish 
between the cartilage true sphenotic, or ear bone, and the 
dermal sphenotic, or lateral line bone, without giving the 
latter a definite name. The subject would repay investi- 
gation. 
Parietal (Par., figs. 1, 5).—Flat conspicuous bones 
containing of course no cartilage. On the dorsal surface 
the inner portion is laminate, but the outer portion is 
much more densely calcified (cp. fig. 1). The boundary 
separating these two parts is where the skull begins to 
shelve down. The two parietals are markedly asymmetri- 
cal, as shown in fig. 1. The parietal is bounded by the 
supraoccipital, frontal, sphenotic, pterotic and epiotic. 
Alisphenoid (A/.S., figs. 2, 3)—Forms, as described 
above, a false floor to the cranial cavity, separating the 
latter from the eye muscle canal. The greater part of the 
dorsal portion of the alisphenoid consists of two thin 
plates of bone with a layer of cartilage between them. 
Behind, the alisphenoid forms the anterior boundary of 
the foramen for the fifth and seventh cranial nerves, and 
it is at this region that the bone is most densely calcified. 
It is bounded by the parasphenoid, prootic, sphenotic, and 
frontal. In front a portion of the border is free. 
Anterior to the parietal region the asymmetry of the 
skull is most emphasized, and its rotation in the direction 
of the hands of a watch is quite manifest. The bones of 
the two sides therefore differ more or less considerably. 
Right Frontal (/?./’r., figs. 1, 2, 3)—Very elongated 
from before backwards and narrowed from side to side. 
It is the anterior prolongation of the right frontal that 
forms the stout bar between the eyes so prominent in the 
E 
