690 



MR. B. F. CUMMIXCiS OX LICE 



copulation. On each side of the basal plate is a large-bellied 

 muscle ai'ising from an abdominal stei'uite some way forward and 

 inserted by a delicate tendon into the lower end of the bnsal 

 plate. These are retractor muscles, withdrawing the appaiutus 

 ■within the body after coj^ulation. The continuous invagination 

 of the SMC is brought about by the contraction of a gi-eat many 

 small muscles arising from the doisal surface of the basal plate 

 and inserted successively along the walls of the sac. They are 

 particularly numerous above tlie ductus at the distal end of the 

 sac, being in.serted just behind the opening (text-tig. 34). 



Extrusion of the sac is probably caused by blood-pressure upon 

 contriiction of the powerful dorso-ventx-al abdominal muscle.s 

 segmentally arranged. 



The above is not offered as a complete account of the mechanism 

 of this complicated apparatus. The manifest lacuna? in tlie 

 description must be filled in only after a great deal more study of 

 the parts. 



CT 



Text-figure 35, 



CT p 



Sub. O.G 



Ijipewus forjiculatiis, S ■ Trnnsvevsp section through the head behind the 

 antenntB. (Diagrammatic.) 



CT. chitinous tendon for attachment of mandibular muscles (ilf.). P. pharynx. 

 T. trachea. Suh.O.G. subcesophageal ganglion. F. eye. 



Mouth-pai'ts. — Labmm : The labial sclerite is present merely as 

 a narrow transA'erse band near the anterioi- margin. Isopogo- 

 metric Apparattcs : Lyriform organ without posterior cornua. 

 Anterior cornua are broad and flat, convex on the outer margin, 

 and in length equal to that of the "nucleus" itself; from each 

 side a chitinous bar runs np the wall of the pharynx, which is 

 further supported dorsall}' by a short median longitudinal splint. 

 Behind the lyriform organ the chitinous intima of the pharynx 

 bears a number of minute teeth. As in Lvpeurus ferox (9, text- 

 fig. 24) there is a. comjjound hypopharynx consisting of a narrow, 

 short, median piece, and on each side a longer rectangular strip. 

 The pharynx (see text-fig. 35) is supplied with numerous small 

 muscles — circular, longitudinal, and transverse. The latter are 

 developed further forward, and consequently do not appear in the 



