520 JULIA B. PLATT. 
olfactory nerve, which is not represented, and with the ramus 
ophthalmicus superficialis facialis. 
The homologue of that branch of the trigeminus which 
fuses with the ramus buccalis is described by Dohrn (8) in the 
Selachii as the ramus “ infra-maxillaris,” by v. Wijhe (38) in the 
Ganoidei as the ramus “ maxillaris superior,’ while Strong 
(36) mentions the nerve in the tadpole as an accessory branch 
of the trigeminus. 
In Necturus this nerve is one of the chief primitive 
branches of the trigeminus, although fig. 22 shows its entire 
present length from the Gasserian ganglion above to the 
point where the nerve is lost in the ramus buccalis, which lies 
immediately below the ectodermic ridge of the infra-orbital 
line. The stage represented is but a transitory one in the 
splitting off of the nerve, which takes place throughout the 
length of the common Anlage. In a slightly older embryo one 
finds two distinct nerves side by side, one belonging to the 
facialis, the other to the trigeminus. The relation of these 
nerves to one another seems to me of interest, because so 
closely resembling that of the ramus ophthalmicus superficialis 
to the profundus. In the one case the supra-orbital ridge gives 
rise successively to two distinct nerves; in the other the infra- 
orbital ridge gives rise to a nerve from which the inner part 
splits off as a trigeminal branch, while the outer part remains 
as a branch of the facialis. The difference in the manner of 
formation is therefore chiefly one of time. A longer interval 
separates the two nerves formed from the supra-orbital ridge 
than that separating those formed from the infra-orbital ; but 
the close similarity of origin suggests that this branch of the 
trigeminus might well be called the ‘ buccalis profundus,” and 
so I have ventured to name it in Necturus under the shelter of 
dissident authorities. 
Dohrn (8, p. 267) says of the “ N. infra-maxillaris ” in Pris- 
tiurus, that many branches pass to it from the infra-orbital 
canal, that these branches have a much more oblique and a 
longer course than those of the buccalis, “ und,—was noch 
auffallender ist—sie gehiéren einem Nervenstamm an, der von 
