EMERSON: ANATOMY OF TYPHLOMOLGE. 
63 
distal end of the first epibranchial on its pharyngeal surface. The 
second and third are short and thinner than the first. They arise 
from the first myocomma of the back muscle, posterior to the tem¬ 
poralis, and pass backwards and outwards to insert respectively on 
the second and third epibranchials, on the pharyngeal surface at their 
distal ends. The fourth is much thicker than either the second 
or the third and arises from the integument of the back by fascia, 
inserting on the outer side of the lateral raphe which extends poste¬ 
riorly from the distal end of the third epibranchial, according to 
Goppert (’ 94 ) and Wilder (’ 96 ) the supposed rudiment of the fourth 
epibranchial. The fifth is in form and origin similar to the fourth 
and probably inserts on the mid-ventral line with its fellow, although 
I was unable to verify this, owing to the fact that the specimen had 
been partially dissected before I received it. It is evident that this 
fifth levator arcus is identical with the dilatator laryngeus of allied 
forms, thus emphasizing the serial homology of this last-named mus¬ 
cle with the other levators. Here they evidently belong to the 
same series and are so treated. 
The hyo-trachialis (the interbranchialis of Driiner) is a thin sheet 
of muscle forming the floor of the pharynx. It is divided into two 
parts, the anterior arising from the posterior border of the middle 
third of the third epibranchial, and the posterior from the inner edge 
of the raphe which represents the fourth epibranchial. Both parts 
insert with their fellows in the mid-ventral line, owing to the absence 
of a trachea. 
Muscles of the Trunk. 
The trunk muscles of Typhlomolge are large thick masses, meta- 
meric in structure and little differentiated (the thoracico-hyoideus, 
described above, is possibly a differentiation of the rectus abdominis). 
Along the back runs a very thick, paired muscle, the two portions 
being parallel and separated only by a narrow band of connective 
tissue containing fat. It arises from the postero-dorsal part of the 
skull and extends to the sacral region where it is continued in a 
ventral direction and is CQntinuous with the lateral muscle of the tail. 
. The fibers run from myocomma to myocomma, a few of the inner 
ones attaching to each vertebra. 
Laterally the trunk is covered from the shoulder to the pelvis by 
