Taenia Caenurus. 247 



communicating' with the lateral trunks by short transverse 

 anastomoses. These vessels are both contractile and ciliated. 

 In their ramifications, besides other excretory matters which 

 they may be supposed^ from the analogy of other allied 

 animals (guanin having been found in the water-vascular 

 system of Trematodes) to contain, crystals of carbonate and 

 phosphate of calcium are found, and sometimes, as in both 

 the other classes of Platyelminthes, in great abundance. 

 These calcareous corpuscles are found both in the central 

 parenchyma and in the cortical layers of the Taenia, but in 

 greatest abundance in the latter strata, into which a dense 

 reticulation of capillary vessels, in which the corpuscles are 

 lodged, may be observed to spread from the larger qviadri- 

 laterally arranged vessels which lie in the central paren- 

 chyma. 



b. Uterus, in the unripe segment running as a straight tube 



from the posterior part of each segment to its anterior. 



c. Ovary, or rather, as the yolk is furnished in these as in other 



Platyelminthes by a separate set of glands, the ^germi- 

 genous^ gland. This organ occupies a place quite at the 

 posterior end of each segment, and has a reticular arrange- 

 ment. 



d. Bilaterally symmetrical yolk-secreting gland or ' vitellarium,' 



lying anteriorly to the germigenous gland. The two stems 

 carrying the digitate processes of either side unite into one 

 common duet ; this common vitelliferous duct joins the 

 vagina just above the spot where it dilates into a recepta- 

 culum seminis. The common duct formed of these three 

 factors carries its two kinds of contents into the dilated 

 end of the uterus, just where it receives the duct from the 

 germigenous gland, the products of which are thus brouglit 

 at once into relation with tlie yolk and the spermatozoa. 

 The granular layer of the cortical stratum which immedi- 

 ately underlies and secretes the chitinous ' cuticular' struc- 

 ture of the cortex, and overlies the muscles, has been 

 sometimes mistaken for the true vitelligenous glands here 

 described. 



e. Testes appended in a racemose manner by very delicate ducts 



to the vasa deferentia. They were more abundant in the 



