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Studies ejii Pediculus 
duct, and retractors running obliquely from the ventral body wall 
to the dorsal surface of the sack, these being the retractors of the sack 
(for which we use the term vesica) whose function we shall describe 
presently. Pawlowsky places the ejaculatory duct within the inverted 
sack, whereas it runs outside excepting where it traverses it at the base 
of the penis. Muller (1915), in his illustrations, refers to the “Bulbus 
Muskulatur des Penis,” muscles called the retractors of the vesica in 
this paper; Muller figures them in a cross section as running dorsally 
to the basal plate. He states -correctly (p. 43) that these muscles are 
inserted in the folds of the sack, but from the name he gives them it 
would appear that he did not apprehend their function. 
The female apparatus. 
A survey of the literature shows that the female apparatus has not 
hitherto been understood. Landois (1865, p. 50) refers to the presence 
of teeth upon the vaginal wall, these being seen by transparency through 
the surface of the body. He figures circular, longitudinal and obhque 
muscles surrounding the vagina (what we term the uterus), but the 
structure and shape of the vagina and its relation to the uterus escaped 
him. Pawlowsky (1907, pis. ii, iii, figs. 4-12) illustrates his paper by 
figures of cross and longitudinal sections of the female. He evidently 
made no dissections and his description is inadequate. His figures 
indicate, however, that the vagina is flattened dorso-ventrally, dentate 
internally; muscles arising from the ventral surface of the abdomen 
run backward to attach themselves upon the dorsal surface of the vaginal 
wall; the proximal half of the ventral wall of the vagina has inserted 
upon it retractor muscles running obhquely forward to the ventral 
surface of the body and it is also traversed by a few muscle fibres which 
he terms sphincter vaginae. These muscles are not to be confused with 
others surrounding what we term the uterus but which Pawlowsky terms 
the vagina (he also terms these muscles sphincter vaginae). 
Muller (1915, pp. 37-41, figs. 21, 22) gives an accurate figure of the 
posterior portion of the female abdomen. He terms the gonopods 
“vaginal palps” and refers to their position as being at the point of 
transition between the last two abdominal segments. He gives a 
misleading schematic figure of the female genitaha for he surrounds the 
uterus by circular fibres only, making it appear bulbous, the vagina 
being represented as a straight, narrow tube, whereas it is broad, purse¬ 
like, and dentate internally. Finally may be mentioned a superficial 
paper by Peacock (1916, p. 39) who describes the external features of 
