ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 379 



spicules reacli so high a pitch as in S. lacustris, although in Meyenia 

 No. 2, the length of the amphidisks and the diameter of their end- 

 disks both vary from '006 to "014 mm. The diameter of the gem- 

 mules of S. lacustris ranged in the Eussian specimens from • 28 to 

 • 4 mm. The gemmule of S. sibirica is remarkable for its two layers, 

 the inner firm, structureless, yellow, the outer thin, colourless, trans- 

 parent, and made up of non-nucleate, polygonal cells. 



A useful list of 84 papers dealing with this group is appended. 



Protozoa. 



Biitschli's Protozoa.— Parts 17-19, with plates XXIX. to 

 XXXVIII. of this work have appeared. The text deals with the 

 Sporozoa. The Gregarinida are divided into the two orders of the 

 Monocystidea and of the Polycistidea, each with 13 genera. The 

 three genera of the latter order lately described by Schneider are 

 subsequently noticed. The wide distribution among the Invertebrata 

 of these parasites is noted, and their common occurrence among 

 mammals is pointed out. The next chapter deals with the Myxo- 

 sporidia or so-called fish-psorosperms, and the spore-formation is 

 carefully described. The lately suggested name of Sarcosporideia 

 (Balbiani) is applied to the " tubes " (sarcocysts) of Miescher and 

 Eainey, the correct relations of which to the Gregarinida must still 

 remain an open question. The figures illustrating the Eadiolaria are 

 completed, and those of the Sporozoa commenced. 



Flagellate Infusorian, an Ectoparasite of Fishes.* — L. F. 

 Henneguy describes an ectoparasite of young trout, which seems to 

 cover their surface. When fixed these infusoriform parasites have the 

 appearance of small pyriform cells, fixed by their narrower end. A 

 clear line divides the body into longitudinal asymmetrical halves, and 

 this line corresponds to a groove in which is placed a long flagellum. 

 When the animal is free it expands and has the form of a Haliotis- 

 shell. If the fish dies the infusorian guest abandons it and 

 disappears, probably to take up its abode on another. In ordinary 

 infusions the parasite cannot live, for fresh water appears to be a 

 necessity of its existence. 



Most nearly allied to Bodo (Amphimonas^ caudatus, it is dis- 

 tinguished by having three, instead of two, flagella; the new form 

 may be called B. necator. This, which appears to be the first de- 

 scribed ectoparasitic flagellate infusorian, seems to cause the death of 

 its host by giving rise to an alteration in the activity of the cells of 

 the epithelium ; for in a young trout the cells appear to be under- 

 going active division, which ceases when it becomes attacked by this 

 parasite. 



Gigantic Actinosphgerium Eichhornii.t — Professor J. Leidy 

 noticed in an aquarium what appeared to be eggs adherent to the 

 edges of the leaves of Vallisneria. On examining the egg-like bodies 



* Comptes Rciuhis, xcvi. (1883) pp. 658-60. 

 t Proc. Acad. Nat. Sci. Philad., 1882, p. 260. 



