256 Annals Entomological Society of America [Vol. V, 
with the abdominal segments. Consequently the description 
of a single segment will answer as a type of all the segments. 
The muscles of the thorax are more complex, due to the muscles 
of the legs. 
Great Dorso-Recti Muscles (g. d-r.m.).—The broad area of 
white, opaque muscles lying to the right and left of the heart are 
the great dorso-recti muscles. Upon a superficial examination 
of the ends of the muscles at the conjunctiva, one might be 
led to think that the muscles were continuous, except for a 
slight depression. But as a matter of fact, they are contiguous 
and separated by a narrow, hyaline, cuticular line at the point 
of the depression. These particular muscles attach themselves 
to the cephalic side of the transverse conjunctiva. 
Small Dorso-Recti Muscles (s. d-r. m.).—Laterad of the 
lateral margin of the great dorso-recti muscles, the small dorso- 
recti muscles are located. This band of muscles consists of 
three to five small fibres that are fastened to the caudal margin 
of the transverse conjunctiva. Laterad of this bundle of muscles 
an area exists, which is free of longitudinal muscles but contains 
the spiracles and their accompanying trachee. 
Great Ventro-Rectt Muscles (g. v-r. m.). If the larvais spread 
out as in Fig. 12, the large band of muscles laterad of the free 
area consists of the great ventro-recti muscles. This group is 
ventrad of the spiracles. These muscles attach themselves to 
the cephalic aspect of the transverse conjunctiva. 
Small Ventro-Recti Muscles (s. v-r. m.).—These muscles are 
located mesad of the great ventro-recti muscles along the ventral 
area of the larva adjacent to the nervous system. They are 
attached to the caudal side of the transverse conjunctiva. All 
these muscles are supplied by trachee. 
Dorso-Ventral Muscles (d. v. m.).—The dorso-ventral muscles 
are the two groups of short muscles that extend dorso-ventrad 
across the free area existing between the great ventro-recti 
muscles and the small dorso-recti muscles, one group at the 
cephalic end of the segment and the other at the caudal end. 
Two fibres, the cephalic group, cross immediately cephalad of 
the spiracle and mesad of the longitudinal trachea between the 
abdominal spiracles and mesad of the small dorso-recti muscles. 
The other remaining fibres disappear dorsally in the cephalic 
part of the segment as the two already described fibres but 
ventrally they cross at an angle the transverse conjunctiva 
