3i8 Records of the Indian Museum. [Voiv. VIII, 



in those animals with a more extended head region they lie slightly 

 posterior to this position. The eyes are about equidistant from one 

 another and from the side of the head^ and each lies in a small 

 area containing somewhat less pigment than the general surface of 

 the body. 



A very distinct non-pigmented area occurs on either side, 

 immediately anterior to the neck, and indicates the lateral sensory 

 cephalic groove ("Auricularsinnesorgan " of German writers). 



The ventral surface is of a milky white colour and possesses 

 only a single aperture, the mouth; the position of the mouth 

 varies very considerably from 2 to 4 mm. from the posterior end 

 of the animal. This is probably due to the fact that the animal 

 multiplies by transverse fission, those animals with the mouth 

 situated well back being those which have recently budded off new 

 individuals. 



Cleared in cedar- wood oil, much of the general anatomy is 

 visible. The pharynx is comparatively long (2 mm. long in a 

 specimen 9 mm. in length) ; the rest of the alimentary tract con- 

 sists of the usual single anterior and two posterior trunks; the 

 secondary branches are very numerous, and in an 8 mm. specimen 

 the anterior trunk sent off about 20 on each side, while the 

 branches of the posterior trunks numbered about 33 on each side, 

 7 alongside the pharynx and 26 posterior to the mouth. The 

 extreme anterior branches of the gut extend as far forward as the 

 eyes. 



From entire mounts and also from serial sections, it was found 

 that the animal had no male generative organs; even the rudi- 

 ments of these organs were missing, as was also a genital aperture. 

 Absence of reproductive organs has been found to be a character 

 of many species, such as P. suhtentaculata (4), P. venusta (i) and 

 P. vitta ; Zacharias considers it to be a feature of P. suhtentaculata 

 during the summer months, and that the sexual organs appear in 

 the autumn. He says: — " . . . es schient, dass die Fortpflanzung 

 durch Ouertheilung nur wahrend der Sommermonate stattfindet ; " 

 and further: " es miissen zur Herbstzeit Eier producirende, resp. 

 geschlechtlich differenzirte Individuen vorhanden sein, und diese 

 habe ich unter den Handen gehabt." However, he does not des- 

 cribe the genital apparatus. Duges also referred to the same thing 

 when he mentioned the likelihood of some small specimens of the 

 same species which he found in the autumn being produced from 

 eggs : ' ' Ces individus ne pouvaient avoir une origine par separa- 

 tion; des oeufs sans doute leur avaient donne naisssance" (3). 



A search between the anterior branches of the gut revealed a 

 definite compact aggregation of cells comparable to the ovary in 

 other planarians, situated on either side of the body. So consis- 

 tent in position and nature are these bodies with the ovaries in 

 other species, there does not seem to me to be any doubt that 

 they are ovaries, though at first I had some hesitation owing to 

 the entire absence of any other genital organs. As will be seen 

 from fig. 3 the cells composing this cell mass are undoubtedly 



