534 THE ANIMAL PARASITES OF MAN 



Genus. Phthirius, Leach. 

 Phthirius inguinalis, Redi, 1668. 



Syn. : Pediculus pubis, L. 



Male 0-8 to ro mm. in length ; female 1-12 mm. in length ; colour 

 greyish-white ; form subquadrate ; the two posterior pairs of legs are 

 strong ; the abdomen has nine segments and six pairs of stigmata ; 

 and still another pair of stigmata is situated between the two anterior 

 limbs. Eggs pear-shaped, o'8 to 0^9 mm. in length, 0*4 to 0*5 mm. 

 in breadth, and are deposited in rows of about ten on the hairs. 



FIG. 378. Phlhirius inguinalis, Leach : they are distinguished by the larger 

 tracheal trunks originating from the stigmata. Enlarged. 



Pediculus pubis^ which is found almost exclusively in the Caucasian race, lives on 

 hairy parts of the body, but hardly ever on the skin of the head ; the pubic 

 region is its favourite place of abode. 



[This species reproduces more rapidly than other lice, and is communicated 

 much more freely. The eggs are often laid singly attached to the hairs near their 

 apex. It is known as the " crab louse." F. V. T.] 



(b) RHYNCOTA HEMIPTERA. 



Family. Acanthiadae. 



Body flattened, antennae four-jointed, rostrum three-jointed, wings atrophied. 



[This family, the CimicidcB^ includes the bed bugs ; the proboscis, which lies in a 

 groove, is of three segments ; the front wings are shown by two small elytra, there is 

 no trace of hind wings. Two species are known commonly to attack man. F. V. T.] 



Genus. Cimex, Linnaeus. 

 Cimex lectularius, Linnaeus. 



Syn. : Acanthia lecttdaria, Fabricius, 1794. 



It measures 4 to 5 mm. in length, 3 mm. in breadth ; brownish- 

 red eight abdominal segments. The female deposits fifty whitish 

 eggs at a time (ri2 mm. in length) three or four times a year ; the 



