36 REVIEWS. 



show that they were not perfect animals ; and (3), that their exceedingly 

 simple structure differed much from that of the Helminthes. Kolli- 

 ker, indeed, considered the simple Gregarinse as unicellular animals. 

 "Without assenting to the theory which this expression involves, we may, 

 in the absence of more valid testimony, agree with the general tenor of 

 his observations, and view the Gregarinse as indubitable members of the 

 group Protozoa. The recent careful investigations of Lieberkiihn^ ap- 

 pear to strengthen this position. 



In the same year wherein Leydig published his researches on the 

 GregarinaB, Professor Huxley described, under the name of Thalassicolla,f 

 a singular genus of marine animals, manifesting affinities both with the 

 Sponges and Foraminifera. It would appear, however, that Meyen, 

 seventeen years before, had noted the existence of some of these forms. J 



The nature of the Thalassicollse was, subsequently, further eluci- 

 dated by the late J, Miiller, who arranged these organisms under four 

 genera : Thalassicolla proper, Physematium, Sphserozoon, and Collo- 

 sphsera.§ He, at the same time, called attention to an allied group of 

 Protozoa, previously unnoticed, which he proposed to term Acantho- 

 metra. These observations are, perhaps, the more interesting, since 

 they form the subject of the last communication made to science by this 

 great anatomist. || 



One other addition to the Protozoa yet remains to be noticed. There 

 can be now little doubt that the ]Noctiluca^[ of Surriry, well known 

 for its power of imparting a phosphorescent appearance to the sea, and 

 erroneously referred by De Blainville to the Diphydae, rightly belongs 

 to this sub-kingdom. From the observations of Professor Huxley, ** its 

 affinities would seem to be nearest the Infusoria, though, by Doyere, 

 Yan Beneden, and others, it has been placed with the Ehizopodous 

 members of the group. 



Thus, then, there exists an extensive group of organisms of very 

 humble structure, but equivalent in Zoological importance to the Yer- 

 tebrata, Mollusca, and other primary divisions of the animal kingdom. 

 This department, or sub-kingdom, of Protozoa contains : — 



1. Reizopoda, including Foraminifera. 



2. polyctstina. 



3. Thalassicollida. 



4. AcANTHOMETRA. 



5. Spongidje, or Porifera. 



6. Gregarinida, including Psorospermice. 



7. Infusoria. 



8. Noctiltjcida. 



* Evolution des Gregarines, Mem. del'Acad. de Belg., torn. 26, 1855. 



f Ann. Nat. Hist., 1851, p. 433. 



J Nov. Act. Acad. Car. Leop., 1834, xvi., Supp. I., p. 159. 



§ Monats-Ber. der Acad, zu Berlin, 1855, pp. 229 and 671 : ibid., 1856, p. 474. 



|| Abhand. d. Berlin Acad., 1858. 



IT Guerin. Mag. d. Zool., 1836, p. 1. 



" "Quart. Jour. Micr. Sci.," 1855, p. 49. 



