702 MEDICAL ENTOMOLOGY 



to open into the oesophagus ; the pharynx or sucking pump is 

 actuated by certain muscles attached to its walls. At the junction 

 of the oesophagus with the intestine there is a marked dilation which 

 probably represents a proventriculus. The intestinal canal is a broad 

 cylindrical tube which lies in the middle of the body and ends in a 

 transverse slit, the anus, just above the caudal end on the ventral 

 side ; in the living condition it is of a dark brown colour, due to 

 the digested blood it contains, and exhibits slow peristaltic movements. 

 On section it is seen to be a wide tube lined by a row of large cylindrical 

 cells, with deeply staining nuclei, attached to a delicate basement mem- 

 brane ; around this there is a layer of circular muscular fibres, and 

 external to these there are a few longitudinal muscular bands. 



Closely applied to the sides of the alimentary tract are the .salivary 

 glands, which consist of groups of acini surrounding a large duct. 



Salivary glands (Plate LXXXVIII > % 2- s.g). The cells are composed 

 of two kinds, large finely granular cells with small 

 deeply staining nuclei and smaller vacuolated cells with somewhat 

 larger nuclei. These cells are arranged in groups to form lobules, 

 from which delicate ducts carry the secretion to the main channel. In 

 the salivary glands of Porocephalus pattoni it is quite common to find 

 the encysted stage of a protozoon (fig. 2, x), which is believed to be the 

 sexual stage of the haemogregarine of the snake, lying in between the 

 salivary cells ; all stages in the development may be seen, from small 

 cysts to large ones full of daughter cysts containing sporozoits. 



On opening a female linguatulid the reproductive organs come pro- 

 minently into view (fig. 8). They consist of a median ovary, a pair of 



oviducts, a pair of spermathecae and an extremely long 

 Female reproductive . , . r 



organs uterus, which is coiled up and when full of eggs occu- 



pies almost the entire body cavity. The ovary lies be- 

 tween the salivary glands and is closely applied to the dorsal surface 

 of the intestinal tract in its lower half ; it is of a dull white colour and 

 exhibits a finely lobulated appearance, due to the presence of young ova. 

 Its structure resembles very closely that of the corresponding organ 

 in the ticks. About the junction of the middle and upper third of the 

 body it divides into two delicate oviducts, which after a short course 

 in contact with the intestinal tract dip down on each side to the ventral 

 surface, and pass round the intestine to unite to form a short common 

 duct, into which enters the duct formed by the junction of the two sperma- 

 thecae. These organs are situated on the ventral surface on each side 

 of the intestinal canal ; they may be recognized by their white colour 



