140 
ME. H. N. MOSELEY ON THE ANATOMY AND 
In Rhynchodemus the testes are not of a definite spherical form as in Bipalium, but 
oval, with one end of the oval drawn out. They are very numerous, packed tightly 
together (Plate XIII. fig. 15), and they extend along each side of the body as far down 
as the base of the penis, instead of stopping short halfway as in Bipalium. I was 
unable to find the vas deferens in the anterior part of the testes of Rhynchodemus ; and 
it is possible that the successive testicular sacs may here communicate directly with one 
another, or that thus the whole testis may here be one long moniliform or contorted 
tube. I had not sufficient material to determine this point. The arrangement of the 
parent and immature cells is the same as in Bipalium. The spermatozoa are linear, 
and resemble those of Bipalium. The losing of the bead-like swelling by mature sper- 
matozoa has been noted by Max Schultze in other Planarians (Max Schultze, loc. cit. 4, 
p. 31). The position of the vas deferens in Bipalium and Rhynchodemus is remarkable 
as being to the inner sides of the testes, since in the leech it is to the outer sides of 
those organs. 
The male and female intromittent organs form a small mass placed just posteriorly 
to the pharynx in an excavation into the median septum between the two posterior 
digestive tubes (Plate XII. fig. 2, G). This mass is seen enlarged in Plate XI. fig. 8. 
It consists in Bipalium of a posterior portion of an inverted flask-shape, with an 
ovoid body attached to it at a slight inclination anteriorly. The narrow neck of the 
flask-shaped body stands vertically, immediately over the external generative aperture. 
At its base anteriorly the body is entered by the oviduct, whilst the ovoid anterior 
mass is pierced by the vas deferens, which first passes backwards beyond its point of 
entrance, and then returns upon itself a short distance with a tortuous course to its 
destination. Plate XI. fig. 6 shows the arrangement of parts within the bodies just 
described. The external generative orifice opens into a short vestibular cavity, into 
which superiorly opens the mouth of the flask-shaped mass ; leading from the mouth of 
this mass is a straight vertical vaginal tube, which at its summit bends sharply towards 
the anterior extremity of the body, and forms a small space, into which open the oviducts? 
hence termed uterus. In the anterior aspect of the vaginal tube close to its orifice 
opens the cavity of the ovoid portion of the generative mass, which consists of the sheath 
containing the penis and its contents : the cavity of the penis-sheath is of the same form 
as that of the sheath. To its internal surface, at its upper and anterior extremity, is 
attached the penis, which in its shrunken preserved state does not reach as far as the 
opening into the vagina. 
The external generative orifice is provided with a circular sphincter muscle, and is 
clothed internally, as is the whole of the vestibule, vagina, and uterus, with ciliated 
epithelium. The vestibule is provided with a muscular wall, consisting of circular and 
longitudinal fibres, with radiating fibres interspersed between them, and serving to hold 
the tubular cavity in place by attaching it to surrounding tissue. The vagina (Plate XII. 
fig. 6 & Plate XI. fig. 9) has a very dense internal circular coat, external to which is a 
thick mass of longitudinal and radiating muscular fibres. 
