W' 



142 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 81 



The muscles of the maxilla may be enumerated as follows, and 

 they will probably be found to dififer but little in different species of 

 caterpillars : 



6. — First adductor of the cardo (fig. 53 B, D, E, F). — Origin on 

 posterior end of anterior arm of tentorium (AT) ; goes ventrally 

 to insertion on base of cardo. 



7. — Second adductor of the cardo (fig. 53 B, D, E, F). — Origin 

 anteriorly on tentorial arm (D, E) ; insertion on distal end of cardo. 



8. — Third adductor of the cardo (fig. 53 D, E, F). — This muscle 

 found in noctuid larvae, perhaps a subdivision of 7. Origin anterior 

 to 7 on tentorial arm (D, E) ; insertion on accessory plate (E, F, k) 

 mesad to the articulating sclerite of cardo {Cd). 



9. — First adductor of the stipes (fig. 53 B, D, E, F). — Arises near 

 anterior end of anterior tentorial arm (D. E) ; goes obliquely ventrally 

 and posteriorly to insertion on marginal ridge (B, D, E, F, q) of 

 stipes. 



70. — Second adductor of the stipes .(^g- 53 B, D, E, F). — Origin 

 at anterior end of tentorial arm, just before p (D, E) ; insertion on 

 stipital ridge (D, E, F, q) anterior to p. 



II. — Third adductor of the stipes (fig. 53 B, D, E, F). — Arises pos- 

 teriorly on anterior tentorial arm, just before first adductor of cardo 

 (6) ; goes obliquely ventrally and anteriorly (D, E), internal to 7, 8, 

 p, and 10, to insertion on anterior end of stipital ridge (B, D, E, F, q) 



12. — External retractor of the lobe (fig. 53 B, F). — Origin on 

 base of stipital ridge {q) ; insertion laterally on basal plate (A, B, /) 

 of terminal lobe of maxilla. 



/?. — Internal retractor of the lobe (fig. 53 B. F). — Origin on 

 base of stipital ridge (q) ; insertion mesally on basal plate (A, B, /) 

 of terminal lobe of maxilla. 



14.- — Cranial abductor of the lobe (fig. 53 B). — Origin in basal 

 angle of hypostomal plate of epicranium (Hst) ; insertion on outer 

 end 'of basal plate (/) of terminal lobe of maxilla. A corresponding 

 muscle is not present in orthopteroid insects. 



The labium of the caterpillar (fig. 53 A) lies between the maxillae. 

 The broad membranous surface of its large submental region is united 

 on each side with the marginal ridges (q) of the stipites, and its 

 basal part is continuous laterally with the membrane of the cardinal 

 areas. Proximally the labium may be continuous with the neck mem- 

 brane (NMb) between the approximated ends of the hypostomal 

 plates (Hst), but, when the latter are united, the labium becomes 



