114 BYRNES. [VoL. XIV. 
regions can have little weight in establishing the dependence 
of the limb-muscles on the myotomes. 
II. NorMAL DEVELOPMENT OF THE MyYOTOME-DERIVATIVES, 
ANTERIOR AND POSTERIOR LIMBS IN THE ANURA 
(RANA AND BuFo). 
What has been said of the relation of the myotome-processes 
to the limbs in Amblystoma applies also in a general way to 
Rana and to Bufo. The Anura differ, however, from the Uro- 
dela in the structure of the ventral myotome-processes and in 
the early separation of the myotome-processes from the myo- 
tomes. Another point of difference between the two forms 
and one which has been taken advantage of in experimenting 
on Rana consists in the increased distance between the ventral 
edges of the myotomes and the limbs (Pl. X, Fig. 18). 
Kaestner! and Maurer? have already given a detailed account 
of the development of the muscles of the body-wall in the 
Anura, and Kaestner has attempted to show the relations of 
the myotomes to the limbs. Inasmuch, however, as the pres- 
ent account of the muscles of the limbs differs from any that 
has been given for Rana, I shall briefly review the early 
development of the myotome-processes during the time that 
they are in closest contact with the limbs. 
In Rana the myotomes give rise to short ventral processes 
which become constricted from the myotomes very early. 
Unlike the ventral myotome-processes of Amblystoma and 
Triton, the ventral myotome-processes of Rana contain no 
myocoel, but appear as solid outgrowths from the ventral edges 
of the muscle-plates (Pl. X, Fig. 18). The ventral processes 
of the anurans are first formed from the myotomes in the 
anterior part of the body. Soon after their formation they are 
constricted from the myotomes and begin to move toward the 
ventral body-wall. Later, the more posterior myotomes give 
rise to ventral processes which likewise become separated from 
the myotomes in the order of their formation. Throughout 
1 Archiv f. Anat. u. Phys. (Anat. Abth.), Hefte 5 und 6, 1893. 
2 Morph. Jahrb., Bd. 22, Heft 2, 1894. 
