218 SUPPLEMENT 
of the second, against which it is cemented more or less 
closely, forming sometimes a sort of epidydymis by its nu- 
merous folds, then is changed into a cylindrical canal with 
thick muscular parietes. ‘This is directed towards a species 
of excitatory organ, at the base of which it terminates in the 
majority of cases. ‘This organ is only a sort of long hollow 
tentaculum, contractile in all its points, of a form extremely 
variable even in species of the same genera, and which most 
generally retracted into the interior of the visceral cavity, by 
the aid of a retractor muscle, may also, from the disposition 
of muscular annular fibres, be turned outwards, like the finger 
of a glove. 
At the point where the deferential canal terminates we 
sometimes find a heap of cylindroid organs, or kind of hollow 
coeca, variable in number, and which successively united at 
their base, finish by opening through a single orifice. These 
have been called the vesicule seminales. 
Finally, in a certain number of hermaphrodite mollusca we 
remark another organ again neighbouring to the external 
termination of the male apparatus. It consists of a muscular 
mucous pouch, in the form of a bladder, which produces and 
contains in its interior a labial corneo-cretaceous’ body, in the 
form of a dart, or poignard ; this body can issue forth through 
the orifice of the pouch, which is situated near that of the 
rest of the male apparatus. 
In spite of the intimate connexion which subsists between 
the two parts of the genital apparatus of these hermaphrodite 
mollusca in their passage, they may terminate at distances 
more or less considerable from one another, although always 
on the right side. Thus in some species the termination of the 
female organ is altogether behind, and that of the male organ 
in front, more or less near the tentaculum on that side, as in 
the veronicellz and onchidia. In some others the separation 
is less great; many have them united in the same external 
—— 
