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SUPPLEMENT 
proximated in consequence of the absence of the viscera, pro- 
ceed from a central point, and form radii at the circumference 
of the discus, which we have said terminates the body of the 
leech, while the circular fibres preserve their usual disposition. 
The apparatus of digestion is pretty similar to that of most 
of the class : there is no evident serous lacuna between the 
exterior and that which constitutes the intestinal canal ; on 
the contrary, these two parts are united by numerous cellular 
and vascular bridles, which pass from one to the other, and 
thus produce a sort of strangulations, and then a series of 
pouches or dilatations of the intestine. 
We have already remarked, that the anterior extremity of 
the leeches presents an aperture more or less considerable, 
conducting into a cavity sometimes conformed like a cupper ; 
at the bottom of this cavity exists a labial fold, composed of 
three lobes, not very distinct, rather narrow, two lateral and 
one ventral, leaving between them a triangular space, the sum- 
mit of which is upwards. In this space appear projecting 
more or less the dentiferous tubercles; these tubercles are the 
same in number as the labial folds, but in an inverse order. 
Their form is sublenticular. They are placed on a level, so 
that the free part of their edge, very obtuse, converges towards 
the longitudinal axis of the body, and the adherent part is 
confounded with the contractile stratum of the external en- 
velope. They are of a yellowish and shining white, and 
appear to be of a denser tissue and more compact than the rest 
of the contractile stratum of which they are a dependence. 
They seem entirely contractile, though there is at their dorsal 
base a muscular fasciculus, more distinct, forming a part of 
the longitudinal stratum, extending under the oesophagus, and, 
besides, another transverse bridle, very visible, particularly 
between the two inferior tubercles. It is on the very blunt 
edge, how r ever, that one can distinguish, by the assistance of a 
glass of very short focus, a double series of corneous teeth, ex- 
