ON A NEW HISTRIOBDELLID. 319 



those of the granule glands. These ridges are formed by 

 accumulated masses of the secretion of these glands. 



The glands which I have termed granule glands, on account 

 of their resemblance to the glands so named in the Turbel- 

 laria and some Trematodes, are situated on each side imme- 

 diately behind the base of the clasper. In each of the two 

 groups there are about half a dozen of these glands, which 

 are pear-shaped and unicellular. The narrow end of each, 

 which is directed inwards, is prolonged into a delicate duct 

 which runs to the seminal vesicle, into which it opens on the 

 ventral side. The rod-shaped granules which the glands 

 secrete are thus mixed with the sperms in the cavity of the 

 seminal vesicles. Sometimes the ducts are found to be dis- 

 tended with accumulated masses of the secretion. 



The vas deferens is a thin-walled, widish tube, which 

 runs inwards to a point in the middle line close to the base 

 of the penis, where it unites with its fellow to form the 

 median ejaculatory duct. 



The penis (figs. 14 — 16) is a hollow chitinous spine, per- 

 forated throughout by the ejaculatory duct. At its base it 

 is produced into three processes, one median and two lateral, 

 for the insertion of the protractor and retractor muscles. It 

 is broadest at the base and tapers gradually distally, ending 

 in a sharp point. At the free end it is cut oif obliquely like 

 the needle of a hypodermic syringe. Near the extremity it 

 bears two very minute spinules, one dorsal and one ventral.^ 

 When at rest the penis lies enclosed in a folded integu- 

 mentary sheath, which projects more or less prominently on 

 the ventral surface, its pointed extremity directed backwards 

 and downwards, and just protruding through the median 

 ventral reproductive aperture. In a good many preserved 

 specimens it was found fully protruded when it extends 

 forwards and slightly downwards from the reproductive 

 aperture at the end of the everted sheath. 



The glands which — their function being unknown — I have 



1 The shape of the penis and its processes differs somewhat iu different 

 specimens. 



