ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 219 



referred to F. vestimenti Nitzsch, occasionally as P. corporis Degeer.) 

 In 1866 Schiodte proved the suctorial nature of the apparatus, but the 

 structure has remained something of a mystery, and the homologies are 

 obscure. 



The stomodeeum is divisible into buccal cavity, pumping-pharynx, 

 pharynx proper, and cBsophagus. Upon the floor of the buccal cavity, 

 near its hinder end, opens a long invagination, the piercer-sheath, which 

 extends beneath the alimentary canal back almost to the occiput, and 

 contains the piercing apparatus. Within the piercer-sheath lie four 

 structures directly continuous with six chitinous tendons into which six 

 muscles rising from the posterior wall of the head-capsule are inserted. 

 The tendons of the dorsal muscles are continued into the dorsal-piercer ; 

 the tendons of the lateral pair of muscles concresce as the ventral- 

 piercer ; the tendons of the ventral muscles expand into a chitinous 

 plate, separable into anterior and posterior portions, which lies embedded 

 in the floor of the sheath. These plates may represent the mentum 

 and submentum of the labium. The fourth structure is a delicate 

 chitinous duct, probably the salivary duct. One important part of the 

 apparatus has hitherto escaped notice altogether — the buccal tube. 

 This is a tube lying free within the buccal cavity, composed of two 

 lateral apposable half -tubes which arise ventro-laterally from the floor 

 of the fore-gut at the point of junction of the buccal cavity and pump- 

 ing-pharynx. Into the lumen of the tube thus formed enter the dorsal 

 and ventral piercers, and the salivary duct. All these parts are dealt 

 with in detail. 



The method of feeding is as follows. When the louse has selected 

 a spot, the haustellum is protruded by protraction of the buccal plate, 

 and a superficial fixation effected by the buccal teeth. The same action 

 brings the buccal tube into contact with the skin, and the contained 

 piercing apparatus enters the tissues of the host, and penetrates to the 

 level at which blood is reached. Salivary-secretion accompanies the 

 piercer, and possibly contains an anti-coagulin and also has some solvent 

 action. The pumping-pharynx commences its rhythmical dilations, by 

 means of which blood is drawn in through the buccal tube, and passed 

 backwards to the pharynx, where, by means of alternate contraction of 

 the sphincters and dilatation of the dilatators, it is pumped backwards 

 into the oesophagus, by the peristaltic action of which it is carried to the 

 stomach. At the close of the feeding-process, the piercer is drawn in 

 by its own retractors, the retractors of the labium serving to pull the 

 sheath back. The retractors of the buccal cavity draw in the haustellum 

 and buccal tube. 



The author maintains that Mallophaga and Anoplura are beyond all 

 question closely related, and that the Anoplura are distinctly nearer, in 

 a great many features, to the Ischnocera than to the Amblycera. The 

 mandible and maxilla may be dismissed as far as any participation in the 

 actual mouth-parts of Anoplura is concerned. The mentum and sub- 

 mentum may be represented by the two plates lying in the floor of the 

 piercer-sheath. The buccal tube and the piercing apparatus are probably 

 altogether due to transformations of the Mallophagan hypopharynx. 



Q 2 



