678 The American Naturalist. [August, 
the floor of the otic capsule to be distributed as usual. The 
facialis branch divides into two portions just outside the era- 
nial wall and behind and below the quadrate; the very large 
posterior branch runs backward to innervate the posterior belly 
of the digastric muscle. The anterior ramus has the usual 
distribution. 
An especially noticeable feature in connection with the 
twelfth nerve is the persistence of the dorsal ganglion. Wald- 
schmidt’s observations on Protopterus and those of von Plessin 
and Rabinowicz upon Salamandra are interesting in this con- 
nection. 
The nasal organ has a well developed organ of Jacobson, 
though on a simpler type than that of the Cecilians. The 
sensory epithelium of the nose, is in these embryos, not differ- 
entiated as in the adult. 
Conciustons.—Following such students of the Batrachia as 
Cope and the Sarasins it is with some diffidence that I dissent 
from their conclusions, for both regard Amphiuma as a con- 
necting link between the Cecilians and the Urodeles. That 
both Gymnophiona and Amphiuma are degenerate goes with- 
out question, but it seems to me that their many peculiar 
resemblances are those of homoplassy rather than derivations 
from a common ancestor. Then again, some of these resem- 
blances have been founded upon mistakes. Thus the possess- 
ion of an ethmoid by Amphiuma cannot be maintained. The 
external gills of the larve are not so similar as has been sup- 
posed ; the derotrematous condition which appears later has 
one important difference: In Amphiuma only the third gill 
slit persists to open through the round external opening to the 
exterior, and my material shows that when the other slits were 
open they had separate openings upon the side of-the neck- 
In Ichthyophis, on the other hand, the observations of the 
Sarasins show that both the second and third slits have a com- 
mon external opening. 
On the other hand, there are certain differences to be empha- 
sized. The presence of an ethmoid in the Gymnophiona (and 
its absence from Amphiuma and other Urodeles’) the exist- 
“The ethmoid of H. H, Wilder in Siren is clearly not homologous with the bone 
eeen called by that name in other vertebrates. It is rather the prefrontal of 
authors. 
