ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 77 



and all the SpTierophryce are able to resume their cilia and become 

 free. The form described is moreover very common, and has been 

 previously published by Claparede. and Lachmann, Fresenius, and 

 Quennersted, as well as by Cohn. He also considers that the assimi- 

 lation of the "suckers" to those of the Acinetidee is a purely gratuitous 

 assumption not resting on any positive observation, the so-called 

 suckers never having been observed to act as such but solely as 

 fixing organs. Further the vibratile appendages of the Acinetidge are 

 always simple vibratile cilia, whilst in Acarella they are compound 

 or true cirri, and represent therefore the higher state of development. 

 M. Maupas adheres to his view * that the ancestral affinities of the 

 Acinetidge are with the Heliozoa rather than with the Ciliata, 



Dr. Mereschkowsky replies | to this criticism, maintaining the 

 correctness of his original paper on all points. 



New Infusorian belonging^ to the Genus Pyxicola.J — Professor 

 J. Leidy describes an infusorian, a species of Pyxicola, which ap- 

 peared to be different from those previously described. It is of fre- 

 quent occurrence, attached to the tubes of Plumatella, Urnatella, and 

 Cordylophora, on stones. In shape it resembles Pyxicola pusilla and 

 P. affinis, fresh-water forms of England, but is annulate as in P. 

 socialis, a salt-water form. It presents the following characters : — 



Pyxicola annulata. Lorica urceolate, slightly curved, inflated 

 towards the middle, tapering below, cylindrical and feebly contracted 

 at the neck, and with the aperture oblique and circular, variably annu- 

 late, mostly at the neck, often at the middle ; colour chestnut-brown, 

 but colourless when young ; pedicle short, always colourless. The con- 

 tained animalcule is of the usual shape, with an attached operculum, 

 which is of the same colour as the lorica, and is protruded beyond this 

 when the animal is fully extended. Length of lorica, • 52 to • 792 mm. ; 

 breadth, 0-02 to 0-0264 mm. ; length of pedicle, -004 to -008 mm. 



Systematic Position of Amphidinium.§ — E. S. Bergh supple- 

 ments his previous observations on the Cilio-flagellata by a note, in 

 which he places Amphidinium with the Grymnodinidse, and not with 

 the Dinophyidee, as he originally proposed. 



Evolution of the Peridinina.il— M. Pouchet brings forward some 

 observations which, he thinks, reveal a new order of phenomena in 

 the genesis of the Peridinians. The different varieties of Ceratium 

 furca and G. tripos always occurred, as usual, isolated, of equal size, 

 and with no traces of any genesic operations, until, on October 9th, a 

 single cast of the net furnished no fewer than three forms of Ceratia, 

 namely, C. tripos and its var. megaceros, and C. furca, arranged in 

 chains of two, three, and up to eight individuals joined end to end. 

 The boat was four or five miles off the shore ; and the depth was 

 80-100 metres. These curious chains are probably formed at the 

 bottom. The mode of union of the individuals is as follows : — The 



* Cf. this Journal, ii. (1882) p. 639. 



t Comptes Kendus, xcvi. (1883) pp. 276-9. 



X Pioc. Acad. Nat. Sci. Philad., 1882, pp. 252-3 (2 figs, of a plate to follow). 



§ Zool. Anzeig.,, v. (1882) pp. 698-5. 



II Comptes Kendus, xcv. (1882) pp. 794-6. 



