Mar., 1903.] 
Spelerpes longimudus. 
3*5 
Musculature. — A careful comparison of the muscles of this 
stage of Spelerpes longicaudus with the musculature of Rana and 
Cryptobranchus seems to show a close resemblance to Crypto- 
branchus, especially in the muscles of the branchial apparatus. 
Of course, no homologues of these muscles appear in the adult 
Rana, but even the larger head muscles correspond much more 
closely with those of Cryptobranchus. There appears to be no 
special modification for sucking, or any special muscles for that 
purpose. All of the muscles described are those of the adult 
Salamander in various stages of development. In the nomencla- 
ture of the muscles of the branchial apparatus, the analogies of 
Cryptobranchus have been very closely followed out. 
MUSCLES OF THE HEAD. 
M. Temporalis. — (Plate n, Fig. i, mtm.) The temporalis 
is the most prominent of the muscles of the head. It arises on 
the quadrate cartilage, just posterior to the second foramen, and 
is inserted on the inner side of the coronary process. It is a 
broad, heavy sheet of fibres, broader at the insertion than at the 
origin. Its direction is ventral and slightly caudal. In reality, 
M. temporalis is made up of two parts, the one just described 
above, and a second, which I shall describe as — 
M. Pterygoideus. — This is a thin strand of fibres arising on 
the quadrate bar, just below the origin of M. temporalis, and 
sending its fibres ventrally to unite with those of the temporalis. 
It corresponds very closely to the similar muscle in Cryptobranchus, 
which is described as follows: “This is a very insignificant 
muscle * * * and might almost be considered a fasciculus of 
M. temporalis. (Thesis, J. H. McGregor.) The muscle is 
entirely covered dorsally by. M.' temporalis, and acts with the 
temporalis in lifting the mandible, in opposition to the action of 
M. depressor maxillae inferioris. 
M. Masseter. — (Plate n, Fig. i, mm.) The masseter is a 
heavy, bulging muscle, partly covering M. temporalis. It arises 
on the anterior third of the auditory capsule, and, running down- 
ward and forward, is inserted on the outside of the mandibular 
bar (Meckel’s cartilage), a short distance in front of the coronary 
process. The insertion of this muscle is comparatively very 
broad, though it is thick-bellied and rounded in the center. 
M. Depressor maxillae inferioris. — (Plates n, Fig. i, 
mdm.). This is a large and powerful muscle, which, using the 
base of the lower mandible as a lever, depresses the jaws. It has 
two origins ; the first in the middle of the optic capsule, just 
posterior to the origin of M. masseter, and a second, which is 
lower and posterior to the first. The fibres from the two origins, 
however, soon intermingle, and evidence of the double origina- 
tion is lost. The muscle extends down and forward, parallel to 
