514 C. GORDON HEWITT. 
are repeated fairly regularly from segments (by segments I 
mean body-segments) four to twelve and a detailed descrip- 
tion of the muscles of one of these segments will serve for the 
rest. The muscles, though continuous in most cases from seg- — 
ment to segment, are attached to the body-wall at the junction 
of the segments. The most prominent muscles are the dorso- 
lateral oblique recti muscles. In segments six to twelve there 
are four pairs each of external (ew. d. J.), and internal dorso- 
lateral oblique recti (in. d. 1.) muscles ; in segments four and 
five there are five pairs of external and six pairs of internal 
dorso-lateral oblique muscles. Ventral to these muscles are 
four pairs of longitudinal ventro-lateral muscles (J. v. l.); the 
muscle bands of the two more ventral pairs are double the 
width of those of the two more lateral pairs. In the fifth seg- 
ment there is only one of the more lateral pairs of the longi- 
tudinal ventro-lateral muscles present, and in the fourth 
segment only the two more ventral pairsremain. In addition 
to these muscles there are two other pairs of oblique recti 
muscles; these are, a pair of ventro-lateral oblique muscles 
(v. l.o.) and a pair of internal lateral oblique muscles (7. l. 0.) ; 
both of these are absent in the segments anterior to the sixth. 
The foregoing muscles, namely the dorso-lateral oblique, the 
internal lateral oblique, the ventro-lateral oblique and the 
longitudinal ventro-lateral, by their contraction, bring togeth er 
the intersegmental rings and so contract the body of the larva. 
Attached externally to the anterior ends of the longitudinal 
ventro-lateral muscles are a number of pairs.of ventral oblique 
muscles (v. 0.) ; they vary in number from two to eight pairs in 
each segment. ‘The number increases posteriorly from two 
pairs in segment four to four pairs in segment five, five pairs 
in segment seven, seven pairs in segment ten, eight pairs in 
segment eleven ; the number of pairs then decreases to six or 
seven pairs in segment twelve. The more ventral pairs of 
these muscles are not attached at their posterior ends to the 
intersegmental ring but to the ventral wall of the segment 
and no doubt assist in bringing forward the ventral spiniferous 
pads. In segments four to twelve there are three pairs of 
