700 Laura Florence 



Nuttall (page 304 of reference cited), " the essential parts of the apparatus 

 are: (1) the basal plate, (2) the dilator (parameres), (3) the vesica penis 

 [preputial sac], including its rib or strut, statumen penis, embedded in 

 its wall, (4) the penis, and (5) the ductus ejaculatorius." In the preceding 

 year Cummings (1916:257) had given the following explanation of the 

 terminology used in describing the male copulatory apparatus of Siphuncu- 

 lata (Anoplura) and Mallophaga: 



In almost all Anoplura and Mallophaga, it is easy to recognise at once the basal plate and 

 the parameres. The basal plate — probably double in origin as two longitudinal apodemes 

 — is a chitinous lamina usually, if not always, longer than broad, to the posterior lateral 

 angles of which are articulated the two chitinous appendages known as parameres. Between 

 the parameres is the mesosome, the parts of which are not so readily made out unless a 

 specimen be carefully dissected. Fundamentally, the mesosome is a sac — the enlarged 

 and extrusible end continuous mth the ductus ejaculatorius. This sac — called by Mjoberg 

 " the preputial sac " — presents two regions of chitinisation — a distal and a proximal. At 

 the distal end is the rod of the penis or virga, with frequently a splint on each side called the 

 telomere, and one below — the hypomere. * At the proximal end are the endomeres, usually 

 strongly chitinised bands or rods, one on each side, supporting the membrane of the sac, of 

 which they are only local thickenings. The whole of the genitalia exhibit enormous variety 

 in form, and the mesosomatic parts in particular are occasionally so much modified that it 

 becomes difficult to recognise their conformation to the general plan just sketched out above. 

 For example, in many Philopterids, such as Docophorus, no sacular portion of the apparatus 

 is recognisable, and the distal chitinisations lie well back within the proximal, the whole 

 forming a solid and compact mesosome. The above terms are, therefore, adopted solely 

 for convenience of description. 



-^ For these terms, first applied to specialised Philopterid forms, see Waterston, Annals of the .S- African 

 Museum, vol. x, pt. 9, 1914, p. 279. 



' In the hog louse the mesodermal reproductive organs of the male (Plate 

 LXIV, 1) consist of two pairs of testes, slender vasa deferentia, seminal 

 vesicles, and a long ejaculatory duct, and the ectodermal organs (Plate 

 LXIV, 1 and 2) of a penis, a vesica penis, a basal plate, and parameres. 

 The testes are oblong-ovate with somewhat bluntly rounded ends, 

 and the individuals of each pair touch at one end, where each opens into 

 its vas deferens, which almost immediately unite to form a single canal. 

 The testes lie on the dorsal wall of the mid-intestine between the meta- 

 thorax and the posterior border of the fifth abdominal segment. Their 

 free ends point respectively cephalad and caudad, and the left pair 

 frequently lie a little anterior of the right. The vasa deferentia are long, 

 very slender tubes lying coiled upon themselves and then passing back- 

 ward to the region of the eighth al)dominal segment, where they pass 

 into the seminal vesicles just below the rectum. The latter are closely 

 apposed to the wall of the mid-intestine and pass directly cephalad to 



