86 



ENTOMOLOGY 



The muscles of the trunk are segmentally arranged most 

 evidently so in the body of a larva or the abdomen of an 

 imago, where the musculature is essentially the same in sev- 

 eral successive segments. In the thoracic segments of an ima- 

 go, however, the musculature is, at first sight, unlike that of 



FIG. 1 06. 



FIG. 107. 



FIG. 1 08. 



adc 



ts 



abc 



--ts 



Muscles of cockroach; of ventral, dorsal and lateral walls, respectively, a, alary 

 muscle; abc, abductor of coxa; adc, adductor of coxa; ef, extensor of femur; h, head 

 muscles; Is, longitudinal sternal; It, longitudinal tergal; Ith, lateral thoracic; os, 

 oblique sternal; ot, oblique tergal; ts, tergo-sternal; ts 1 , first tergo-sternal. After 

 MIALL and DENNY. 



the abdomen, and in the head it is decidedly different ; though 

 future studies will doubtless show that the thoracic and cepha- 

 lic kinds of musculature are only modifications of the simpler 

 abdominal type modifications brought about in relation to 

 the needs of the legs, wings, mouth parts, antennae and other 

 movable structures. 



The muscular system has been generally neglected by stu- 

 dents of insect anatomy ; the only comprehensive studies upon 

 the subject being those of Straus-Durckheim (1828) on the 

 beetle Melolontha; Lyonet (1762), Newport (1834) and 

 Lubbock (1859) on caterpillars; and the more recent studies 

 of Lubbock and Janet on Hymenoptera. 



