TIN: DENDRorn i \ 



161 



known as Planarice belong to this division. Some arc ma- 

 rine, some fresh-water, and SOUK tin trial. 



In the fresh-water forms, tin- 1< m.il reproductive appa- 

 ratus has a distinct vitellarium, as in the higher Hlml><lu.l(i, 

 and there is only one common genital aperture. But, in tin- 

 marine Planarice (Fig. 33), there is no vitelhuimn ; tin* ova- 

 ries and testes are numerous, and scattered through the meso- 

 denn, being connected with the exterior by ramifications of 

 tin oviducts and of the vasa deferentia. A ramified gland, 

 which secretes a viscid albumen or envelope for the eggs, 



(Ltptophina} laevigata (.after Quatrcfa^fsV a. month; ft, buccal 

 cavty; c, crsophairi'nl orilice ; rf, stomach ; e, ramiflcutionfl <>r -iistric cteca; /, 

 nnglia ; fj, tcstcs ; //. vcsicnhi- seiniiinlos i, male genital canal and peuis ; *, ovi- 

 ducts ; I, spermathecal dilatation at their junction ; m, vulva, 



opens into the vagina, and the female is distinct from the 

 male aperture. Planaria dioica is unisexual. 



In some of the Planarice there are distinct water-vascular 



