50 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
chondrocranium. The two ends of this transverse portion are slightly 
curved in a posterior direction. The teeth, of which there are from 
twenty to thirty, are small and pointed, growing out from the ventral 
surface. 
The two posterior processes of the premaxillary are thin splinters 
of hone arising from the posterior border of the middle third of the 
transverse portion. Posteriorly they are contiguous, forming a fora¬ 
men, the fontanelle, between their anterior portions. Their ventral 
surfaces articulate posteriorly with the dorsal surface of the frontals. 
The vomers together form a dentigerous arch. These two bones are 
thin plates with their inner borders contiguous posteriorly and sepa¬ 
rate anteriorly. The dorsal surface of each is quite smooth, articu¬ 
lating with the parabasal, but the ventral surface has an anterior and 
lateral ridge on which is a single row of twenty or more teeth. 
The palato-pterygoids are irregular narrow plates, each abutting 
posteriorly on the anterior border of the trabeculo-quadrate isthmus 
and articulating antero-dorsally with the parabasal and anteriorly 
with the vomer. Elsewhere they are free from the skull. On its 
antero-lateral border, each palato-pterygoid bears a row of six or 
eight teeth, continuous with the row on the vomer. 
This skull, on comparison with those of other Urodelous forms, 
most closely resembles the skull of the Spelerpes larva. The 
single premaxillary, the bony otic capsules in which the cartilage 
bones are not differentiated and in which the parachordal region of 
the chondrocranium is not distinct, the lack of cartilaginous or bony 
nasal capsules, the arrangement of basi- and supra-occipital arches, 
and the fact that the operculum is entirely separate from the para- 
quadrate, are characteristics common to Typhlomolge and the Speler¬ 
pes larva, both of which differ in all these points from both Necturus 
and Proteus. 
Vertebral Column. 
The vertebral column of Typhlomolge is made up of about fifty 1 
1 The number and description of vertebrae given here were taken from the 
larger of my two specimens. In the smaller there were but twenty-eight caudal 
vertebrae. A comparison of these numbers with the following table taken 
from Gadow may be of interest: — 
No. trunk vertebrae. No. caudal vertebrae. 
Necturus 
19 
29 
Proteus 
30 
28 
Spelerpes fuscus 
16 
23 
