1920] Dii Porte: Muscular System of Gryllus 45- 



G. The Tenth Segment. 



LONGITUDINAL MUSCLES. 



(a) Sternal. 



122. The Ventral Muscle (Fig. 35) is a short flat muscle 

 lying across the inner end of the pedical plate. Probably the 

 homologue of the first ventral muscle of the anterior segments. 



(b) Tergal. 



•123. The Dorsal Muscle (Fig. 35), a homologue of the first 

 dorsals of the anterior segment lies near the median line of the 

 suranal plate, stretching from the anterior to the posterior 

 borders of the sclerite. This and the preceding pull the edges 

 of the anus forward, probably aiding in the ejection of the 

 faeces. 



DORSOVENTRAL MUSCLES. 



(a) Tergo-sternal. 



124. The First Dorsoventral (Fig. 35). From the lateral 

 side of the anterior edge of the suranal plate into the anterior 

 edge of the podical plate near the insertion of the first ventral 

 of the ninth segment. Pulls down the podical plate, enlarging 

 the anal orifice. 



125. The Second Dorsoventral (Fig. 35). From near the 

 hinder end of the suranal plate into the podical plate a short 

 distance in front of its hinder border. Closes the anal orifice 

 by bringing the edges of the suranal and podical plates together.. 



(b) Noto-cercal. 



126. The Adductor of the Cercus (Figs. 34 and 35). From 

 the median line of the suranal plate into the inner side of the 

 base of the cercus. 



127. The Depressor of the Cercus (Figs. 34 and 35). From 

 the anterior edge of the suranal plate into the ventral side of 

 the base of the cercus. 



128. The Elevator of the Cercus (Figs. 34 and 35) originates 

 laterad of the origin of the depressor and is inserted into the 

 dorsal edge of the cercus. 



129. The Abductor of the Cercus (Figs. 34 and 35). From 

 the anterior edge of the lateral portion of the suranal plate into- 

 the outer edge of the cercus. 



