ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 81 



0. acrobates is one of the commonest and at the same time one 

 of the most interesting of the Infusoria to be met with in the Bay of 

 Naples. The dorsal surface of the body is covered by a complete 

 cuirass formed of prismatic rods closely applied to each other ; the 

 cuticle of the ventral surface is traversed by longitudinal grooves 

 which bear the cilia. At the hinder end of the body is a strong 

 structureless process which can be retracted ; the mouth aperture is 

 slit-like and bent, its sides are strengthened by a circle of rod-like 

 bodies. 



These species, as well as a large number of others, are described 

 in great detail. 



New Infusorian Parasite.* — C. Kerhert gives the name of Ghro- 

 matophagiis parasiticus to a protozoon which appears to be the cause 

 of the small white spots which, in the spring of 1884, appeared to be 

 endemic among the fishes in the fresh-water aquarium of the Zoological 

 Gardens at Amsterdam. The infusorian was distinguished by its 

 remarkable size, having a long diameter of 0-615 mm. and a breadth 

 of 0'408 mm.; the body- wall consists of a thin delicate cuticle, 

 regularly covered by very fine cilia ; there are a large number of con- 

 tractile vacuoles of very various dimensions ; trichocysts were not to 

 be detected. The nucleus was horseshoe-shaped. The pigment- 

 granules were grouped into masses of various sizes; the mouth was 

 lateral in position and there was a well-developed pharynx ; there is 

 no anus, and the faeces were seen to escape from various points of 

 the body. Eeproduction is effected, not by fission, but, after separa- 

 tion from the epidermis of the fish on which they are parasitic, and 

 after a certain amount of free life, by a process of encystation which 

 is succeeded by division ; this always goes on in the dark. The 

 process of division within the cyst takes about five hours ; when it is 

 completed the young forms make their way to some fish and on its 

 epidermis complete their development. The parasite appears to 

 belong to the family of the Trachelocercidte of Saville Kent, and, if 

 Kerbert's conclusions are correct, that author's family of Ichthyo- 

 phthiridas must be eliminated from our list. 



New Parasitic Infusoria.t — A. C. Stokes describes some new 

 parasitic Infusoria. Opalina jjava n. sp., so called on account of its 

 colour, inhabits the rectum of the spade-foot hermit toad (Scaphiopus 

 holhrooTci). The colour, which appears to be a stain and not an 

 aggregation of particles, is collected in a layer near the cuticular 

 surface, with a quite sharply defined line of demarcation between the 

 lower margin and the internal body-sarcode. Its numbers are not 

 great, neither is it always to be found. Compared with its more 

 numerous associates, this yellow creature is a giant among pygmies. 

 Its length is from 1/330 to 1/350 in. 



Associated with the foregoing amongst a throng of Bacteria, 

 Bacilli, &c., was found a flagellate infusorian : — ExecJdyga acuminata 

 n. gen. et sp. is more or less ovoid in form, with a somewhat pointed 



* Nederl. Tijdschr. Dierk. Amsterdam, v. (1884) pp. 44-57 (1 pi.), 

 t Amer. Natiu-alist, xviii. (1884) pp. 1081-6 (4 figs.). 

 Ser. 2. — YoL. V. q 



