189 
an important relation to 
the swallowing of bubbles S PELER PES 
of air for pharyngeal brea- he EG 
thing and would be of much 
greater advantage than the 
employment ofthe separate 
muscles in their original 
form. 
In consideration of this 
it seems probable that the 
scapular element represents 
the original dorso-tra- 
chealis and that the 
attachment to the scapula 
is secondary. In the nor- 
mal condition the dorso- 
POR PHY RIT IC US 
Rarve (Epi. 8, ¥) 
digas Pharyngis 
 Aorto Larymgeons, 
8 a Oesophageal 
Fig. 6. Anatomy of laryngeal ee 
region of Spelerpes porphy- 
riticus. X 2. The superficial 
muscles, shoulder girdles and heart 
have been removed. 
trachealis arises from the dorsal integument and runs directly 
beneath the scapula, the inner surface of this bone coming in direct 
contact with its outer surface. When, by the reduction of the trachea 
its insertion is transferred to the oesophagus, a larger organ and much 
harder to dilate, it would necessarily increase its surface of origin, 
and would naturally use for this the inner surface of the scapula 
with which it was originally in contact. 
It seems, then, that Spelerpes presents a stage beyond Plethodon 
in the perfecting of a lungless type, and thus furnishes indications of 
what goal is to be acquired. 
This seems to be, 1) loss of all the laryngo-tracheal muscles as 
distinct elements. 2) The formation of a sheet of transverse fibres 
covering the ventral wall of the pharynx from the os thyroideum 
to below the sternum. 3) The retention and enlargement of the 
cranial origin of the most anterior fibres, and secondary attachments 
of the others to the scapula and to the dorsal trunk muscles. 
Batrachoseps. 
The conclusions concerning this genus are based upon a series of 
cross-sections of. Batrachoseps attenuatus taken through the ventral 
half of the head and neck, which was detached by continuing the 
angles of the mouth posteriorly, and thus dividing the pharynx along 
its lateral walls. 
