ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 605 



filled with cysts, which varied in size from that of a pin's head to that 

 of a pea. When the inner face of the cyst is examined, it is found to 

 be covered with small buds, bi-, tri-, or quadrigeminate. At first 

 sessile and hemispherical, they become spherical and provided with a 

 pedicle, and at last take on a cylindrical form; they then detach 

 themselves from the wall of the cysticercus, and continue to elongate. 

 These forms are not sexually mature, but such forms are often found 

 in the intestines of the same perch. In some examples in which 

 remains only of the cysts were observable, the author found the 

 parasites making their way through the parenchyma of the liver, or 

 in the ducts of that organ. We have, then, here another example of 

 the two stages in the life-history of a Tasnioid parasite, represented 

 in the body of one and the same host. 



Eye of Planarians.*— Professor E. Hertwig finds that the nervous 

 system is very primitive in character, and is but slightly separated ojff 

 from the surrounding tissue ; in the eye, it is possible to distinguish 

 a black pigmented and a clear colourless portion. The former lies 

 along the animal's axis ; the latter is just below the epithelium, and 

 is only separated from it by the basal membrane. The pigmented 

 portion, again, consists of two parts, a transparent nucleus (vitreous 

 body) and a superficial layer of surrounding pigment-cells, which are 

 only wanting at the diaphragm-like point at which the retina or 

 colourless part is connected with the rest. The cylindrical fibres of 

 the vitreous body are arranged parallel to one another, the nucleated 

 ends being nearest the pigment. The retina is only formed of optic 

 cells, which are continued at one end into a nerve-fibre and at the 

 other into a rod-like process. The fibres of the optic nerve traverse 

 the retina in a very irregular manner, so that there is no regular 

 arrangement of the optic cells. 



Ecldnoderniata. 



EcMnoderms from the North Sea. f — Messrs. Danielssen and 

 Keren describe a new genus of the family Asterinidse, to which they 

 give the name of Tylaster (T. Willei), in which the dorsal mar- 

 ginal plates are rudimentary ; and another which they call Poranio- 

 morpha (P. rosea). They also describe as new species Asterias spits- 

 hergensis and Solaster glacialis ; Asterina tumida var. tuberculata is 

 also described and figured ; the species A. tumida was fii'st placed in 

 the genus Solaster by its describer Stuxberg. 



Echinoderinata of the Straits of Magellan, t — Professor Jeffrey 

 Bell describes four new species of the genus Asterias — A. Brandii, 

 A. alba, A. ohtusispinosa, and A. negleda ; a species of Pentagonaster 

 (P. paxillosus), hitherto recorded only from Australia, would seem to 

 be a member of the South American fauna. Cyceihra is the name of a 

 new genus, " which, though generally goniasterid in character, seems, 



* Jen. Zeitschr. f. Naturwiss., xiv. (1881) Suppl. Heft, pp. 55-6. 

 t Nyt Mag. f. Naturvid., xxvi. (1881) pp. 177-95 (2 pis.). 

 J Proc. Zool. Soc. Lond., 1881, pp. 87-101 (2 pis.). 

 Ser. 2.— YoL. I. 2 S 



