ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 385 



a third vas deferens, or there may be self-coj)ulation, the erected 

 penis being received into the adjoining female duct, or, lastly, the 

 genital cloaca may come into function, its opening to the exterior being 

 closed by muscles, the contraction of which drives the expelled sperm 

 into the vagina. As to the form now under consideration, we know 

 that there is no third vas deferens, and that the penis would have to 

 be extraordinarily bent to be able to enter the adjoining female 

 orifice ; while, finally, the absence of a genital cloaca excludes the 

 possibility of self-fertilization by its aid. The author describe:5 the 

 mode by which he supposes two of these hermaphrodite Trematodes 

 may fertilize one another. 



The system of excretory vessels may be, in Trematodes, ordinarily 

 divisible into three parts ; the first of these, the central organ, which 

 is distinguished from the other parts by its muscular investment, was 

 not detected in the new genus. At the hinder pole of the body there 

 are to be seen two well-developed canals, which pass forwards and 

 are, at about the middle of the body, provided with lateral branches, 

 two of which are much longer than the third ; from these there again 

 arise fresh lateral branches, which end blindly and never anastomose 

 with one another ; these ducts are bounded by a doubly-contoured 

 membrane, which is regarded as being certainly a continuation of the 

 external cuticle. Within this, and, especially, applied to its walls, 

 are granules of some size, and high refractive power. The author 

 was unable to detect the ciliated infundibula described by Fraipont 

 and Pintner. 



In his account of the nervous system, Fischer directs attention to 

 structures which appear to represent ventrally placed and peripheral 

 ganglionic cells, the presence of which is of especial interest when 

 we know that the ventral body-muscles are particularly well developed 

 in this form. 



The parenchyma of the body is composed of cells which vary 

 greatly in form and appearance ; at the anterior pole of the body they 

 are smaller and rounder than at the hinder end ; when largest, they 

 have a striking resemblance to those of plants. 



The specimens for examination were hardened in absolute alcohol, 

 coloured with picrocarmine or haematoxylin, sometimes with an 

 ammoniacal solution of carmine. They were rendered transparent 

 by oil of cloves, and by being set up in Canada balsam and chloro- 

 form for permanent preparation, or in glycerine when the sections 

 were not intended to be preserved. 



Polycladidea.* — A. Lang has published the first half of his 

 monograph on these v^^orms. It will be remembered that the author 

 has divided the Turbellaria (the Nemertinea being excluded) into 

 Polycladidea, Tricladidea, and Ehabdocoelida. He now subdivides 

 the first suborder into two tribes : — I. P. acotylea, where we have 

 the three families of Planocerid^, Leptoplani^lae, and CestoplanidsB; 

 and II. P. cotylea, including the Anonymidee, Pseudoceridfe, Eury- 



* Fauna u. Flora des Golfes von Neapel, Monographie xi. (1884) part i., 

 240 pp. (24 pis.). 



Ser. 2.— Vol. IV. 2 D 



