ANATOMY AND HISTOLOGY OF PLEUROCH ATA MOSELEYI. 491 
which are thick and muscular ; the pharynx is bound to the body wall by a 
quantity of muscles running in every direction, in the interstices of which lie 
the pharyngeal glands ; these glands are compound and tubular, and appear to 
ramify everywhere among the muscles of the pharynx. Their presence is noted 
by PerRiIER* in Pontodrilus, but according to CLAPAREDE,t they are absent 
from the earthworm. After the pharynx comes the cesophagus, which is folded 
several times upon itself, so as to occupy only one or two segments; the 
-eesophagus is entirely unprovided with glands, and in this respect Plewrocheta 
differs from most other worms. In Pericheta Houlleti, t for example, there are a 
great many variously specialised cesophageal glands ; and in many other types, 
such as Urocheta, there are the so-called glands of Morren, opening into the 
cesophagus, which in the common earthworm have been termed the “ calciferous 
glands.”§ The gizzard, which forms the next division of the alimentary canal, is 
somewhat pear-shaped, the broad end lying towards the fore part of the body. 
The posterior portion of the gizzard has enormously thickened muscular walls, 
the anterior portion (see Plate X XVII. fig. 8) is thinner and more glandular ; 
its walls are thrown into longitudinal corrugations. The walls of the gizzard 
secret a chitinous layer which forms a perfectly continuous structure attached 
to the walls of the gizzard only at its two extremities ; it presents the appear- 
ance of a cone of stiff white paper with various prominences and folds; its 
shape will be understood from a glance at fig. 8, where it is drawn in position in 
the interior of the gizzard. This cuticular lining exhibits in thin sections a 
certain structure: the whole membrane is perforated by a series of minute 
canals, and the inner half appears distinctly granular, while the outer half, with 
the exception of the canals, is homogeneous. The histological structure of the 
walls of the gizzard is not remarkable. There is an inner layer of tall columnar 
cells, which are about ‘0125 mm. in length and ‘0005 in breadth, and an outer 
layer of muscular fibres arranged in a direction transverse to the long axis of 
the gizzard, forming in fact a circular coat; near to the epithelium lining the 
gizzard there are also a set of muscular fibres running at right angles to circular 
muscles, radiating outwards from the epithelium ; these fibres are, however, 
interspersed among the circular fibres, and do not form a distinct layer. 
Leading out of the gizzard, we have the intestine, which is primarily divisible 
into two portions,—an anterior “small intestine,” which extends from the 8th 
to the 16th segments, and a posterior “ large intestine,” which occupies the rest 
of the body, and is itself divisible into several regions. The small intestine is 
* PrRRIER, loc. cit. 
+ Cuaparnpe, loc. cit. 
+ Perrier, “Mémoires pour servir a lhistoire des Lombriciens terrestres,” MVouvelles Archives du 
Muséum, 1872. 
§ Vide Darwin on Harthworms, London, 1881. 
