156 Macitray Memorran Voume. 
the internal longitudinal layer is an irregular incomplete layer of circularly arranged 
fibres. The internal lning membrane is non-nucleated, appears homogeneous and 
may be cuticular. 
The intestine is small, unbranched, with a small undivided cavity; the wall can, 
even less than in Zemnocephala, be described as a complete epithelium—no division 
into cells being visible. 
V.—Excretory anpD Nervous Systems; RepropuctivE OrGans. 
Neither in the living condition nor in sections have I been able to see excretory 
vessels. The contractile terminal sacs, so readily recognisable in 7emnocephala and 
Craspedella, are here completely absent ; and I can find no trace of external excretory 
apertures. That an excretory system is present is evidenced, however, by the 
presence of vibrating flames. One of these was observed in the middle of each 
tentacle, not far from its extremity, and one or two in various parts of the body. 
The brain occupies the same position, in front of the pharynx, asin Zemnocephala, 
and as in other forms consists of a fibrous band with symmetrically arranged lateral 
groups of ganglion-cells. The arrangement of the nerve-cords is not traceable in my 
preparations. If we except the taetile cones, there are no organs of special sense. 
The single genital aperture leads into a genital cloaca (fig. 5, g.), into the interior 
of which the cirrus projects on the left-hand side. The cirrus (c.) resembles that 
of some of the species of Zemnocephala,—of tubular form, wider at its proximal than 
at its distal end, with an introvert armed with numerous uniform, relatively long and 
sharp spines. 
The two pairs of testes (fig. 1, 2.) are both of rounded form; the posterior pair are 
situated far back near the posterior extremity of the body; the anterior pair just 
behind the intestine. Each testis has its own vas deferens; on either side the two 
vasa deferentia soon combine to form a common vas deferens—right or left as the 
case may be. The right and left vasa deferentia open close together into the 
elongated vesicula seminalis, which is similar to that of Temnocephada. 
The receptaculum vitelli (figs. 1 and 5, ~v.) resembles the corresponding organ 
in Temnocephala, and occupies a similar sub-median position just behind the intestine. 
It has a thick, protoplasmic wall with a small number of large nuclei similar to 
those of the ova. The ovary (ov.) is of oval shape, closely applied to the right-hand 
side of the receptacle. It is precisely like that of Zemnocephala, with the narrow 
pyramidal ova extending transversely across it. In the short division of the oviduct 
leading to the ovary are three remarkable, curved, pointed (chitinous ?) spines or 
