474 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1931 



The presence of endite lobes on the basis is particular!}^ charac- 

 teristic of the gnathal appendages. The presence of two such lobes, 

 lacinia and galea, is typical of the maxillae of crustaceans and insects 

 {^. 19, Lc, Ga). The maxillary lobes are usually movable. When 

 the lobes are provided with muscles, the muscles always (in insects. 



FiauRE 19. — Diagram of the structure and musculatuie of 

 the first maxilla of an insect 



a", basal articulation with cranium; Cd, cardo ; et, coxo- 

 trochauteral Joint ; fga, flexor of galea ; flee, cranial 

 flexor of lacinia ; flcs, stipital flexor of lacinia ; Fm, 

 femur ; ft, femoro-tibial joint ; Oa, galea ; I, dorsal 

 promotors ; J, dorsal remotor ; KLt, tentorial adduc- 

 tors ; LB, limb basis ; Lc, lacinia ; O, levator of palpus ; 

 I'lp, palpus ; Ptar, praetarsns ; Q, depressor of palpus ; 

 rtmxa, anterior rotator of maxilla ; St, stipes ; Tar, 

 tarsus ; Tb, tibia ; Tlpd, telopodite, or palpus ; Tnt, 

 tentorium ; Tr, trochanters. 



at least) take their origin in the stipes (flcs, fga), except a muscle 

 often associated with the lacinia (fled), which arises on the head 

 wall, and therefore apparently belongs to the dorsal promotor system 

 (/) of the basis. 



The mandibles have each only a single terminal lobe. In the 

 Diplopoda the mandibular lobe is freely movable on the basis, and is 



