595 
But little work has been done upon the Amphibian tonsils, 
so far as the writer has been able to ascertain, upon any side, — oceur- 
rence, location, structure or development. A few scant statements 
alone comprise the literature of the subject. HorL (1885) described 
(pp. 223—4) in Salamandra maculata lymphoid infiltrations of the 
epithelium symmetrically placed in the floor of the mouth. Later 
(1889) in a short paragraph (p. 78) he speaks of similar structures 
which he designates as tonsils occurring in the roof of the mouth of the 
frog (Rana temporaria). OPPEL (1889) described in Proteus on each 
side two tonsils directly behind the articulation of the jaw and dor- 
sally at the first branchial cleft. He later (1900) includes the above 
references in an admirable resumé dealing with the entire subject of 
the lymphatic structures in the mouth and pharynx of vertebrates. 
WIEDERSHEIM (1909) simply states that tonsils occur in amphibia 
without giving any reference for the statement. GOEPPERT (1906) in 
the HERTwIG Handbuch observes that in the amphibia the develop- 
ment of the tonsils has not been traced. 
In this study, two forms have been examined in the greatest 
detail, — Salamandra atra as an example of the urodele amphibia, 
and the toad (Bufo lentiginosus) from among the anura. Adult 
(metamorphosed) individuals of Amblystoma punctatum, Desmo- 
enathus fusca, Diemyctylus virescens, Plethodon cinereus, and Gyrino- 
philus porphyriticus were also examined in comparison. In all cases, 
the examination was made by means of serial sections through the 
head. Detailed description follows. 
Salamandra atra. In some 12 regions of the mouth and pharynx 
tonsil-like structures were found to be present in this salamander, as 
follows: — I. In the esophagus a short distance caudad of the pharynx 
and glottis opening, ventrally placed; II. Dorsally, at the same general 
level; III. Laterally, in the oral cavity (pharynx) in the general region 
of the articulation of the jaw (see subsequent description); IV. In the 
floor of the mouth about the cephalic border of the glottis; V. Medially 
located, at the base of the tongue; VI. Lateral to the tongue, over 
the expanded hyoid (ceratohyale); VII. In the floor of the mouth, 
farther cephalad and laterad than VI. VIII. In the roof of the mouth 
in the wall of the recess caudad of the choanae. IX. Upon the dorsal 
surface of the tongue. X. Upon the under (ventral) surface of the 
tongue. XI. Medially in the roof of the mouth in a recess between 
the vomero-palatine bones. XII. In the conjunctiva. 
38* 
