110 Macrteay Memorrat Vouume. 
granular pigment* (PI. x. fig. 1) lying superficial to the layer of longitudinal muscular 
fibres, but extending also in exceedingly fine scattered filaments throughout the whole 
thickness of the parenchyma, and, as in certain Rhabdoceeles, according to Béhmig, 
entering into the central substance of the cerebral ganglion. In the case of 7. 
guadricornis (PI. xiv. fig. 4) the pigment is also partly between the two layers of muscle, 
but is in great measure diffused throughout the whole of the underlying parenchyma; in 
this species it appears as regular larger and smaller spherical granules instead of threads. 
In 7. Nove-zealandie (Pl. x. fig. 7) it is much the same, except that the granules are 
smaller and less uniform. In 7: szxor, on the other hand, the pigment is almost 
completely confined to the zone underneath the layer of circularly-arranged muscular 
fibres, where it is arranged in the form of a network of limited extent with coarse 
irregular meshes, the pigment here appearing, when examined under a high power, 
in the shape of mimute rounded granules. 
Muscular fibres are very numerous in the parenchyma of 7emmnocephala. They 
are slender fibres with small nuclei, either running singly or in bundles. Most of 
them are dorsi-ventral in their course, with varying degrees of obliquity: at their 
extremities they are inserted into the basement membrane. These dorsi-ventral 
bundles are especially numerous in 7. fasczata. They are intimately united with the 
network of the parenchyma, and perforate certain of the large cells lying therein. 
The muscular layers which invest the various organs are of the same character as 
these dorsi-ventral fibres ; but these may be conveniently considered along with the 
organs they enclose. 
VILL.—-Atmentary Canat. 
The mouth, as already noticed, is on the ventral surface a little behind the level 
of the eyes and the excretory openings. When closed it is in the form of a trans- 
verse slit with folded and puckered edges; but it is capable of being opened very 
widely, so as to admit of the passage of comparatively large objects. The mouth 
leads almost directly into the pharynx, a mouth-cavity being here represented only 
by a very small space, lined by a continuation of the integument. The unicellular 
glands, which Weber represents as opening in this position, do not occur in any of 
the species I have examined. 
The pharynx of Zemnocephala is a muscular bulb of rounded shape (pharynx 
bulbosus) with walls of very firm and tough consistency. Its antero-posterior, 
vertical and transverse diameters are almost equal; it occupies about a half to a 
* These are not stellate pigment cells as supposed by Braun; in fact, they are not cells at all. 
