STRUCTURE OF SEVERAL FORMS OF LAND PLANARIANS. 279 



mass consists of the uterus ; the next contains the accessory bulb 

 of the penis ; the next the bulb of the penis itself and part of 

 the ejaculatory duct ; and the fourth or most anterior the vesicula 

 seminalis and upper part of the duct. 



There is a single pair of ovaries present, and these organs are 

 situate at a distance from the anterior extremity of about one sixth 

 the length of the body, on either side of the main digestive canal 

 and close to the outside of its wall (PL XX, fig. 3, o). The oviducts 

 spring from the outer sides of the ovarian sacs and pass directly 

 down the length of the body to reach the uterus, maintaining a 

 similar position in the deeper muscular structures to that which 

 they hold in Bipaliura and Rhynchodemus, as is seen in PI. XX, 

 fig. ^,o,d. 



The testes consist of very numerous small ovoid bodies which 

 are so dispersed as to form a band stretching from a point just 

 posterior to the position of the ovaries to the level of the hinder 

 end of the pharynx. A wide vas deferens, which is tortuous, as in 

 Bipalium and Ehynchodemus, leads from the hinder end of the 

 testes transversely inwards to the vesicula seminalis. The 

 oviducts pass above the vas deferens in their course to the 

 uterus. 



Together with the two specimens of planarians Mr. Travers 

 brought me preserved in the same spirit several of their egg cap- 

 sules. These capsules were perfectly spherical and varied in diameter 

 from 6 mm. to 4| mm., being as large as an ordinary pea. Their 

 walls were firm and resistant, and of a very dark brown or almost 

 black colour. The walls are composed of a thin continuous 

 sheet of a dark brown chitinous substance, which is highly elastic 

 and rolls up into scrolls when torn into fragments. The brown 

 substance shows no definite structure, but only fine granules 

 partly scattered evenly through a homogeneous base, partly 

 gathered into patches in it. 



The egg capsules were found to contain from four to six 

 embryos (PL XX, fig. 7), which lay quite free within the cavities of 

 the capsules, and closely packed together, being curved up to 

 accommodate themselves to the confinement. In one capsule the 

 embryos were in a comparatively early stage. They were in form 

 much wider in proportion to their length than the adults, and 

 flatter, resembling more in form aquatic planarians. 



In the more advanced stages the embryos were of nearly the same 

 form as the parents, and had their oral apparatus already well de- 

 veloped. Each had further a pair of broad dark stripes on its dorsal 

 surface, the stripes being disposed so as to leave a mesial light band 

 between them. This colouring does not correspond with that of 

 either of the adult species which I examined. It may change 

 with advancing development^ or the egg capsules may have 



