infusoria. 
Prot , 4 
Tintinnus ussowi, id. 1. c. p. 150, pi. x. fig. 40, Solowetzky Is. 
Epistylis halanorum, id. 1. c. p. 169, pi. xi. fig. 17, pi. x. fig. 37, Solo- 
wetzky Is. 
Zoothamnium marinum^ id. ?. c. p. 157, pi. x. fig. 36, White Sea. 
Cothurnia arcuata^ id. 1. c. p. 155, pi. x. figs. 8 & 8 a, Solowetzky Is. 
Cothurnia furcifer^ Hutton, J. R. Micr. Soc, i. p. 49, woodcut, New 
Zealand. Has an operculum. 
Dinophysis arctica, Mereschkowsky (4), p. 177, pi. xi. fig. 19, White Sea. 
Hypotricha. 
Oxytricha v)rzesniowskii, Mereschkowsky (4), p. 162, pi. x. fig 33, and 
0. oculata^ id. (4), p. 163, pi. x. figs. 9 & 10, Solowetzky Is. 
Chilodon propellans^ Engelmann (1), p. 122, Utrecht. 
Heterotricha. 
Aspidisca andrewi, Mereschkowsky (4), p. 166, pi. x. fig. 42, Solo- 
wetzky Is. 
Balantidium (P) medusarum^ Mereschkowsky (4), p. 168, pi. x. fig. 11, in 
Medusae, and Worms, White Sea. 
Holotricha. 
Holophrya hessleri, Mereschkowsky (4), p. 171, pi. x. figs. 29 & 30, 
Wologda and Lake Onega. 
Glaucoma wrzesniowskii,, Mereschkowsky (4), p. 169, pi. x. figs. 27 & 27 5, 
Northern Dwina and Lake Onega. 
SUOTORIA. 
Acineta crenata, Fraipont (2), p. 287, pi. vi. figs. 1-11, Belgian coast. 
A. vorticelloides, id. (2), p. 290, pi. vi. figs. 12-17, Ostend. A. divisa^ 
id. (2), p. 792, pi. ii., Belgian coast ; development by budding beneath 
the surface. 
Ophryodendrium helgicum, Fraipont (2), p. 776, pi. i. Belgian coast ; 
development given. 
Podophrya truncata, Fraipont (2), p. 293, pi. vi. figs. 20-26, becomes 
encysted. P. henedeni, id. (2), p. 264, pis. iv. & v., Ostend. 
Podophrya conipes^ Mereschkowsky (4), p. 173, pi. x. fig. 39, pi. xi. 
fig. 16, White Sea. Apparently derived by descent from P. lynghyi. 
Sphcerophrya hydrostatica^ Engelmann, Zool. Anz. i. p. 162, Utrecht, 
surface of water. Besides the numerous small contractile vacuoles, an 
immense air-bladder, of about one-fourth the volume of the body, under- 
lay the cuticle in an observed example, and slowly disappeared, causing 
the body-walls to shrink in. 
Anatomy and Physiology. 
The liquid contained in the contractile vacuole must be expelled out- 
wards, as the body moves suddenly forwards at the moment of contrac- 
tion, without a corresponding movement of the cilia, and because part 
of the body collapses without any increase in the volume of the rest of it, 
in the species observed ; (1), p. 121. 
The trichocysts of Infusoria (3) are solid, and without membrane, and 
not homologous with the Ccelenterate thread cells. Polynuclear condi- 
tions of Infusoria are merely transitory. 
