24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94 



180, 181. Muscles of the spiracles. — The spiracular muscles are 

 alike in segments II to VIII, and the description of those of the 

 second spiracles {165, 166) will serve for each of the following 

 spiracles. 



MUSCLES OF THE EIGHTH SEGMENT 



The muscles of the eighth segment are quite different in the male 

 and the female. The musculature of this segment in the male (fig. 12) 

 conforms with that of the preceding segments except for the reduc- 

 tion of the internal dorsals to a single broad band of fibers on each 

 side {242), and in the absence of the first internal lateral. In the 

 female most of the usual muscles are retained in modified form, but 

 there are several muscles pertaining to the ovipositor and the ovi- 

 ducts that have no counterparts in the male. The muscles of the 

 eighth segment of the female are as follows : 



242, 24s. Internal dorsal muscles (fig. 14). — A transverse series 

 of six longitudinal groups of fibers on each side of the eighth tergum 

 (VIIIT), inserted posteriorly on the apodeme and anterior margin of 

 the ninth tergum (IXT). The lateral muscle on each side (^43) 

 is much larger than the others. 



244. Paradorsal muscle. — Absent in the eighth segment of the 

 female. 



24J. Median external dorsal muscle (fig. 14). — A broad muscle 

 arising on the posterior margin of the eighth tergum, the fibers con- 

 verging anteriorly and mesally to their insertions on the anterior 

 apodeme {Ap) of the ninth tergum. 



246. Lateral external dorsal muscle. — Absent in the female. 



24"/. Median internal ventral muscle. — A slender muscle arising 

 anterolaterally on the eighth sternum (fig. 13), inserted posteriorly 

 on the median apodemal process of the anterior intervalvula of the 

 ovipositor (fig. 17 D). 



248. Lateral ventral muscle. — This muscle arises at the base of the 

 apodeme of the eighth sternum (fig. 13) as in the preceding seg- 

 ments ; but it is attached posteriorly in Dissosteira on the anterior basal 

 sclerite of the first valvula of the ovipositor (fig. 17 A, B, E), and in 

 Melanopliis (fig. 20 C) on the lateral pocket of the genital chamber. 



24p. External ventral muscle. — Absent in the female, unless repre- 

 sented by the depressor of the first valvula (fig. 17 A, B, 2^2). 



2^0. Internal lateral muscle (figs. 13, 14). — A very large triangular 

 muscle arising laterally on the eighth tergum, its fibers spreading ven- 

 trally to their insertions along the entire lateral margin of the eighth 

 sternum (fig. 13). This muscle evidently corresponds with the second 



