ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 899 



is simple, unpaired, and devoid of any uterus or copulatory pouch. 

 The testicular products do not seem to be formed by any sjiecial 

 gland, but are merely developed in the peri-enteric portion of the 

 mesoderm. 



The third species, Prorhynchus stagnalis, has no eyes, and its 

 skin has no rhabdites, but, in their places, there are a number of 

 unicellular glands ; the ciliated pits are less deep than in Microstomum. 

 The next species described is the Gyrator hermaphroditus of Ehren- 

 berg, G. ccecus of Graff. 



Otomesostoma morgiense is most interesting on account of its 

 frontal auditory vesicle, which is in direct relation to the bilobate 

 cerebral ganglion ; it is perfectly round, and its spherical otolith is 

 suspended in a clear and homogeneous liquid ; it is always completely 

 at rest. On either side of the vesicle there are triangular pigment- 

 spots, and it is possible that the organ has, at one and the same time, 

 the function of an auditory and optic apparatus. 



Mesostoma productum, M. lingua, 31. rostratum, and M, trunculum 

 are next described. Typldoplana viridata is the only species in the 

 lake which is known to be of a green colour. This is duo to the 

 presence of unicellular parasites, which have a symbiotic relation to 

 the worm. 



Vortex intermedins is a new species, the testes of which are paired 

 and compact, and open into a large bilobate seminal vesicle. The 

 newness of the species is a matter of doubt ; it may be only a variety 

 of V. truncatus. 



Plagiostoma lemani ( = Planaria lemani Graff) is regarded as being 

 the most important discovery among the deep-sea invertebrates of 

 the lake. The intestinal tube has no muscular layer or special tunic 

 of connective tissue, but rests directly on the mesoderm. There is, 

 in fact, between the intestine and the skin nothing but a vast space 

 which is filled up by a reticulated connective tissue with distinct nuclei 

 where the fibres cross one another. The digestive sac is lobulated, 

 the proboscis is protrusible, and the sexual organs follicular in cha- 

 racter ; by all these points this species shows itself to be intermediate 

 between the Ehabdocojla and the Dendrocoela. 



The author concludes by stating that this list of species is not to 

 be regarded as being a complete catalogue of the Ehabdocoela of the 

 lake. 



Physiology of a Green Planarian.*— A. Barthelemy gives an 

 account of his observations on Convoluta schultzii, in which especial 

 attention is given to the chlorophyll-corpuscles, the physiology of 

 which has already been investigated by Geddes. The author is 

 inclined to look upon their presence as an example of the symbiosis 

 of a unicellular alga and an acoelato worm, and he objects to the ex- 

 periments of Geddes on the ground that they were carried on on a very 

 large superficial area of Planarians. He finds himself that the bubbles 

 of gas arise from fragments of sand or debris, and not from the animal ; 

 and, he asks, how could it be otherwise, when there is a continual 



* Comptcs Rcndus, xcix. (1884) pp. 197-200. 



