ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
743 
Free-swimming Sporocysts.* — Dr. M. Braun has found a number 
of examples of a free-swimming sporocyst, of which only one had as 
yet been seen, in an aquarium in which various freshwater Gastropods 
had been recently placed. But, whereas the unique American specimen 
was only 1 mm. long, his were 6 mm. in length, and they were not 
quite transparent. Their bodies have a T form, the azygos limb being 
band-like in cross-section and thickened to a knob at the free end. In 
this last there was a yellow opaque corpuscle which was seen to be a 
coiled up Distomum ; the paired limbs form lamellar, movable 
appendages. 
These sporocysts came, it was ascertained, from Limnseus palustris 
var. corvus ; they were discovered to be enormously developed Gercarise, 
and only differ from Gercaria macrocerca and G. cystophora in having a 
furcocercal form. The only fish seen to swallow them were goldfish, 
but in these no Distomata were found. For the present this interesting 
form may be known as G. mirabilis. 
Structure and Development of Taenia longicollis.f — Dr. v. Linstow’s 
present memoir is a contribution to our knowledge of the Taeniae of Fishes. 
All these combine to form a small and distinct group, which are distin- 
guished by the absence of a rostellum with hooks at the apex of the 
scolex. Very little is as yet known as to their minute structure, so that 
the author takes the opportunity of giving an account of T. longicollis 
from Osmerus eperlanus. 
Although Dr. v. Linstow has found various Fish-Taeniae, this is the 
first case in which he has found one with sexually mature proglottid s ; 
it is probable that the proglottids only mature in the summer. The 
Fish-Taeniae form an intermediate stage between the Taeniae of warm- 
blooded animals and that family of Cestodes which Diesing called the 
Paramecotyleae. The cuticle is very fine and appears to be homogeneous ; 
the cutis is *0026 mm. thick and is unstained by colouring matters; it 
exhibits a fine radial striation, but does not deserve the name of 
epidermis, as it does not consist of cells. Behind it there is a circular 
and then a longitudinal layer of muscles, while the parenchym is 
traversed by separate and feebly developed dorso-ventral muscles. The 
hypodermis or subcutaneous layer is remarkably well developed, and 
consists of closely pressed, large, vesicular cells with one or more 
rounded nuclei. The parenchym consists of cells with a very remark- 
able flask-like structure ; from the nuclei septa pass to the outer 
membrane of the cell. In T. longicollis there are no calcareous corpuscles, 
though these bodies have been observed in other Fish- Taeniae. The 
suckers on the scolex are circular, and in addition to the ordinary four, 
there is a fifth of half their size ; they consist of cuticle, equatorial, 
meridian, strong radial, again meridian, and again equatorial muscles. 
The ganglonic cells of the brain are unipolar ; two primary nerve-cords 
arise from the brain and pass down the sides within the inner longi- 
tudinal layer of muscles; they are semi-ovate in cross section, *026 mm. 
broad and *011 mm. thick. 
The vascular system is formed of two larger longitudinal trunks 
* Zool. Anzeig., xiv. (1891) pp. 368-9. 
t Jeuaische Zeitschr. f. Naturwiss., lv. (1891) pp. 565-76 (1 pi.). 
