122 Macieay Memoriat Vouume. 
those of 7. fasciata. In this, as in several other particulars, the species described 
by Weber appears to be of simpler organisation: the eye in 7. Semperi he describes 
as a mere spot of pigment lying directly on the ganglion and enclosing two or three 
spherical bodies, which may be of a refractive nature. In the Australian and New 
Zealand species (Pl. x1. figs. 6, 7 and 9, and PI. xi. fig. 2) there is always a cup, 
deeper or shallower, of dense pigment (Z. c.), contained in which and projecting from 
whose mouth is a body of a light pink hue (~. 4.), which we may presume to be a 
refractive body. In the pigmented species the pigment-cup is completely continuous 
with the general pigment layers of the body. The contained body proves, when 
examined in sections, to consist of two distinct parts, differmg in their appearance 
and in their affinity for staining agents. The one part (c.), that which projects from 
the mouth of the cup, has the appearance of a nerve-cell closely applied to the mouth 
of the cup, and contains a nucleus. The other part, that which fills up the interior 
of the pigment-cup, is non-nucleated, and appears very minutely fibrillated; in 
some sections it presents the appearance of being partly divided in its deeper part 
into segments by means of a series of fissures. In 7° szznor (Plate xu. fig. 2) there 
projects through the aperture of the pigment-cup, round its margin, a circlet of short 
thick cylindrical (7) bodies continuous with the central substance in the cavity of the 
cup itself. Embedded in a mass of pigment which projects on the inner side of the 
pigment-cup there is in 7. fasceata and 7. Dendyi a spherical body, which in the 
fresh state appears very clear and glassy, and which does not readily colour with 
staining agents. It contains in its interior a large nucleus similar to that of one of 
the excretory cells. At the base of the cup are several nerve-cells (x. c.), one short 
process of each of which enters the eye; while the other is continued into a nerve 
fibre which enters the brain, forming a short optic nerve. 
Connected with the pigment-cup of the eye are bundles of fibres of the 
pig 
parenchyma muscle, which probably have the function of altering the position of the 
organ. Similar muscular strands have been described by Lang as connected with the 
eye in 7rtstomum. 
XI.—Mate Repropuctive OrGans. 
The genital cloaca is a dorsi-ventrally compressed median cavity, opening by a 
small transverse slit-like aperture in the middle lime of the ventral surface, a little 
distance in front of the sucker. It is lined by a continuation of the cuticle, epidermis 
and muscular layers of the general body wall. Into its interior on the left-hand side 
projects the cirrus, while on the opposite side is situated the female opening. 
