ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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y. Platyhelminthes. 
Freshwater Nemerteans.* — M. J. de Guerne has been impelled by 
Dr. du Plessis’ “ very surprising discovery ” of Nemerteans in the Lake 
of Geneva to draw up a short account of the various species recorded as 
inhabiting fresh water. It is certain that one or more species have 
gradually become definitely accustomed to fresh water. Nemerteans 
appear to have quite a special plasticity for adapting themselves to the 
most varied conditions of existence. 
Original Habitat of Bipalium Kewense.| — Prof. F. Jeffrey Bell 
called attention to the fact that this worm was found by him in a col- 
lection made at Tongatabu by Mr. R. B. Leefe. As it had also been 
found at Samoa, and exchanges of plants had been made by Kew Gardens 
with Fiji, it is probable that this group of islands is the original home 
of the species. On the other hand, Prof. W. Baldwin Spencer J found 
it in Queensland during his recent visit there in search of Ceratodus. 
Genital Apparatus of Tristomidae.§ — Dr. G. Saint-Remy has inves- 
tigated the structure of the genital apparatus in Tristomum molse , 
Phyllonella solese, Pseudocotyle squatinse, Microbothrium apiculatum, and 
Udonella pollachii. On the whole, these forms exhibit great similarity. 
The male apparatus always consists of the same organs, but they vary in 
the extent to which they are developed. The number of testicles may 
be one ( Microbothrium , Udonella ), two, or many ; they are always situated 
in the middle of the body ; they are always bounded by a connective 
envelope, though it is true that it is very delicate, and only slightly 
differentiated from the surrounding tissue. The efferent canal is always 
long and sinuous, and is in some cases provided with a seminal vesicle. 
In some genera there are special glands which secrete a fluid which is 
mixed with the spermatozoa. The ejaculatory apparatus always consists 
of a vesicula ejaculatrix under the influence of more or less powerful 
muscles, and of a canal which is enclosed in a penis, except in Udonella, 
where the copulatory organ is absent. The erectile part of the penis is 
formed of an elongated body which is almost completely muscular ; it 
is lodged in a deep invagination of the ventral wall of the body. In all 
the genera studied, except Tristomum, there is a genital cloaca. 
The female organs are likewise constructed on a general plan, and 
it is only in the copulatory apparatus that any important modifications 
are to be found. The “ germigenous ” organ is always single, and 
rarely multilobate ; the germiduct varies in character on its course to 
the ootyp ; the muscular apparatus described by Vogt as drawing out 
the genital products is found only in Phyllonella ; in the other genera 
the movements are due to the accumulation of products and to the con- 
tractions of the body. The shell-glands which secrete the substance of 
the test are always unicellular, and are so elongated and filiform that 
it would be difficult to recognize them for what they are, but for one’s 
knowledge of them in other types. They are the bodies which Vogt 
took for the muscular fibres of his “ orifice degluteur.” 
* CR. Soc. de Biol., April 1892. See Ann. and Mag. Nat. Hist., x. (1892) 
pp. 197-200. 
f Proc. Zool. Soc. Lond., 1892, p. 258. 
j Nature, xlvi. (1892) p. 306. 
§ Arch, de Biol., xii. (1892) pp. 1-55 (2 pis.). 
