W. M. Fontaine— Geology of the Blue Ridge. 93 
the integument. After confirming the contrary observations of 
Reichert, on the embryo pig, he concludes that “the first of 
the seven branchial fissures of the embryo skate is converted 
into the spiracle, which is the homologue of the Eustachian 
tube and the outer ear-canal.” After a full discussion of the 
homology of the upper jaw in sharks and skates, under the 
light afforded by his investigation of the embryo skate, he sug- 
gests that the cartilage which extends from the olfactory fosse 
toward the pectoral fin is the probable homologue of a maxil- 
lary bone, and that in the lobe the homologue of an intermax- 
illary; that if so, the skates and proteiform reptiles agree in 
having the nostrils open in front of the dental arch ; that while 
in ail Batrachians the nasal groove becomes closed, in the skate 
it remains permanently open; and finally that this view, i 
confirmed, “will add another feature which justifies Owen, 
Agassiz and others, in dissenting trom Cuvier so far as to give 
the Selachians a place in the zoological series higher than that 
of the bony fishes. But at the same time, it will give corrobo- 
tative proof of the correctness of Cuvier’s view, that ‘the rudi- 
ments of the maxillaries, and intermaxillaries,. ... are evi- 
dent in the skeleton.’ ” 
[To be continued. ] 
Art. XL—On some Points in the Geology of the Blue Ridge of 
Virginia ; by Wm. M. Fonrarne. 
[Concluded from page 22.] 
MY next examination was made in the vicinity of Lynch- 
burg, sixty miles southwest of this point. There the James 
ri 
fo 
