i 
674 The American, Naturalist. [August, 
oticus and palatobasale being as yet undeveloped. Behind, 
from the posterior angle, is a projection with which articulates 
the cylindrical process opercularis (columella), the posterior 
end of which is imbedded in the still membranous opercular 
membrane (stapes of Hay), which closes the foramen ovale. 
Meckel’s cartilage articulates with the lower angle of the quad- 
rate, a process extending behind the articulation, for the inser- 
tion of the digastric muscle. The two halves of the lower jaw 
are united by fibrous connective tissue in front. I find no trace 
of Hay’s pterygoid cartilage. The hyoid and branchial arches 
call for no remark aside from the fact that they lack the yoke 
which binds together the upper ends of the branchial bars in 
Amblystoma embryos, and, according to Stöhr, in some other 
orms. 
OssIFIcaTIons.—These have been well described by Hay and 
only a few words are necessary. The ossifications are here, as 
Weidersheim has pointed out for all urodeles, perichondros- 
toses. They consist of, in the cranium at this stage, premax- 
illary, vomeropalatines (better dermopalatines), parasphenoid, 
frontals, parietals, squamosals or tympanics, occipital and small 
patches surrounding the exits of the vagus nerves. In the 
lower jaw dentary and angular bones are seen, while ossifica- 
tion occurs on the hyoids. The premaxillary at thissecompara- 
tively early stage shows no trace of a double origin, either in 
front or in that median osseous process extending backwards, 
which separates the two nasal cavities. This is the septum 
osseum of Weidersheim, and is clearly a portion of the pre- 
maxillary. It is also, I think, the same bone which Cope has 
called ethmoid, and upon which both he and the Sarasins have 
placed great weight in their association of the Gymnophiona 
with the Amphiumide. The squamosal of Amphiuma is 
clearly not homologous with that bone which Weidersheim 
(and following him Cope) has called by that name in the Cæ- 
cilians, but to which the Sarasins have applied the name jugal. 
The ossification of the occipital region is peculiar. As is well 
known the occipital region of the urodele skull is formed by | 
the junction of a primitively separate vertebra with the para- 
chordals and otic capsules. In this vertebra, above its carti- 
