710 HaAroLD HEATH, 
of the intestine. As they proceed down the digestive tract they 
become smaller, uniformly granular and usually dissolve entirely 
though it is not an uncommon thing to find them in the excreta in 
the cloaca. 
The intestine. of practically the same calibre, throughout, makes 
its way by a fairly direct route (usually to the right of the mid 
line) to the front end of the pericardium. Here it bends abruptly 
downward and passing beneath the cloaca opens to the exterior in 
the mid line (Fig. 8). Its epithelial lining forms five or six 
longitudinal folds and appears to be ciliated throughout its entire 
extent, certainly in all but the rectal portion. The cells are chiefly 
columnar and contain varying amounts of some secretion that is 
strongly affected by osmic acid and but little with the ordinary 
stains. In addition to these elements the anterior half of the gut 
is abundantly supplied with another type of gland cell whose 
secretion is deeply stained with haematoxylin. 
Vesicular and even cartilage-like supports are absent in this 
species, their place being taken by two greatly developed and compact 
masses of connective tissue with an admixture of muscle fibres, 
Together these form an ovoid body (Figs. 11, 16) upon which the 
radula rests and to which several muscles attach that are in part 
responsible for the movements of the teeth (see page 715). In the mid 
line these supports are near together and are firmly united by small 
bands of muscle that will be described later. In front their upper 
surfaces are in close contact where the exposed portions of the 
radula rest upon them but farther backward they separate to allow 
the radula tube, and more ventrally the great muscle No. 1, to pass 
between them. 
The various muscles of the anterior end will now be described 
in detail after which an attempt will be made to define their 
respective functions. 
No. 1. The largest muscle directly attached to the radula 
supports is this bundle which may be termed the tooth adductor. 
As may be seen from Figs. 3, 5, 15 it is roughly cone-shaped and 
anteriorly attaches to the sides and bottom of the posterior end of 
the posterior end of the epithelial fold projecting between the radula 
supports. Farther backward additional fibres appear and become 
increasingly more numerous until they cover the entire under sur- 
face of the radula tube as far back as the insertion of the pharynx 
retractors. Still more posteriorly its fibres become united with those 
