ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 261 



peduncle, which is slightly broadened out at its base. The whole 

 surface is very distinctly marked out by transverse striae ; there is a 

 delicate crown of cilia at the point wliere the anterior passes into the 

 posterior two-thirds of the body ; these do not move regularly but 

 intermittently. The nucleus is large and triangular, occupies the 

 middle of the body, and contains one or more nucleoli ; when there 

 is one it is triangular, when there are more they are rounded. The 

 author observed a stage of encystation, but was, unfortunately, unable 

 to follow out the developmental history ; in some young forms the 

 crown of small cilia was completely wanting. 



Peridineae.* — M. G. Pouchet publishes a third contribution to the 

 history of the Peridinese, describing a number of forms which he has 

 recently observed, viz. Protoperidinium viride, Peridinium tabulatum, 

 Gymnodinium crassum, Gymnodinium polyphemus, and Prorocentrum 

 micans. 



In regard to P. tahulatum, he reports the occurrence of a 

 quiescent phase of cell-life, observed in September, and lasting for 

 several months, during which the organism exhibited an almost 

 spherical form, a thick inner, and a delicate outer cuticle, granular 

 protoplasm apparently collected in small spheres, a constant mass of 

 red pigment, and only an indistinct trace of the nucleus and of the 

 grooves. He comes, however, to no conclusion as to the physiological 

 import of this resting stage. 



He corroborates his former descriptions of G. crassum, and 

 figures a beautiful preparation of the nucleus (due to M. Fabre- 

 Domergue, and fixed by a mixture of osmic acid and methyl-green) 

 in which the coiled nuclear filaments are seen somewhat contracted, 

 leaving a clear space between them and the thick double-contoured 

 nuclear membrane. 



He compares the G. polyphemus observed with that described in 

 a former report, and notes several peculiarities — the twisting of 

 the axis, the all but invisible nucleus, the very marked, terminal, 

 cap-like plate, &c. He emphasizes the differences in size, and in 

 the presence or absence of the cyst, which obtain among these 

 Pohjphemi or Peridinece with eye-spots. He figures two individuals 

 within a cyst, apparently resulting from a fissiparous division. The 

 eye was observed as a hyaline rod, having the anterior or oral end 

 plunged in a cylindrical mass of granular, black pigment. 



Great numbers of Prorocentrum micans were found, uninjured, 

 among the excrement matter of a Comatula, and in these M. Pouchet 

 was able to corroborate his previous observations of this species, in 

 its encysted and cyst-changing stages. He contrasts the pear- 

 shaped, escaped form, with that observed within the test. The 

 formation of the new test, and the resumption of the characteristic 

 features are described. 



Peridinium and other Infusoria.f — Dr. A. C. Stokes confirms 

 E^lebs' statement that the equatorial groove of Peridinium contains a 



* Journ. Anat. et Physiol. (Eobin), xxi. (1885) pp. 525-33 (1 pi.). . 

 t Jouin. Trenton Nat. Hist. Soc, i. (1886) pp. 18-22. 



