140 THE ANATOMY OF AMPHIPTYCHES URNA. 
concerned with the reproductive organs. On the dorsal side, slightly anterior to the 
level of the first-mentioned opening, and about half-way between the margin of the 
body and the middle line, is a third opening. These three openings were recognised 
by Wagener, but he was apparently unable to determine the meaning of two of them, 
the first mentioned and the third; the second he rightly recognised as connected 
with the female organs. Of these openings the first is the male opening, the second 
that of the duct of the receptaculum seminis, and the third that of the uterus. 
By means of making the body transparent the greater part of the structures can 
be determined, so far as their macroscopic anatomy is concerned. Series of 
consecutive sections enable us to more minutely and exactly investigate the structure 
and connection of the different organs than was possible when the worm was first 
described, and the study of three such series leads me to a somewhat different 
interpretation of certain structures to that placed upon them by Dr. Wagener, and to 
a more complete account of the various structures present, and the relationship, 
especially, of the ducts to the various organs of the reproductive system. 
(1). Structure of Body Wall and Musculature.—What is, perhaps, the most 
prominent feature of the body wall, the presence of very distinct and numerous spines, 
has been described by Wagener. They are distributed generally over the body surface, 
but are most numerous along the side folds, and more especially at the anterior end, 
both on the dorsal and ventral surface, and again at the posterior end, beyond the 
region of the side folds. They are sparsely distributed over the central part of the 
body, both dorsally and ventrally. Only the somewhat rounded point of each 
protrudes externally, and is placed at the apex of a minute papilla. The spines 
(Pl. 13, Figs. 5, 6, and 18) are somewhat elongate in form, with a slightly swollen 
internal end, to which special muscle fibres are attached, which are so arranged that 
on contraction they serve to extrude the spine. Hach spine, as the figures show, is 
composed of concentric layers of a transparent material, and when cut in transverse 
section is circular in outline. 
The whole of the body is covered with a cuticular layer; beneath this lies the 
epidermis, consisting of long, thin, columnar cells, which pass internally into a layer 
of apparently homogeneous material. The character of the epidermic cells is the 
same everywhere, except on the inner surface of the folds of the rosette at the anterior 
and on the walls of the space holding the proboscis, where the cells become (Pl. 12, 
Vig. 9) glandular and goblet-shaped. The function of these gland cells is difficult 
to imagine unless it be that of secreting a sticky material, enabling the parasite to 
adhere to the walls of the alimemtary canal of its host. 
Next to the epidermis lies a layer of smooth muscle fibres running circularly 
round the body. Within this (Pl. 18, Fig. 3) is a layer of longitudinally arranged 
