84 E. RAY LANKESTER, ON GREGARINID&. 
some a sort of process projects from one end of the body, 
frequently provided with a circle of reflexed hooklets, which 
in the bilocular Gregarinz is attached to the anterior sac. 
There is no appearance whatever of a mouth in these animals, 
and they appear to live by a process of absorption through 
the membranous envelope. ach sac contains in its interior 
a mass of granules varying in quantity, which by reflected 
light appear whitish and semi-opaque, but when viewed with 
transmitted light are seen to be transparent, and of a yellow 
colour. In the posterior sac a clear and well-defined vesicle 
is situated, which sometimes contains granules and a nucleus. 
The membrane of which the sacs are formed is transparent 
and contractile. In some species the existence of a second 
tunic within the posterior sac has been ascertained. 
Dufour described six species of these parasites, all of 
which were bilocular. 
Dr. Hammerschmidt, in the ‘Tsis von Oken,’ 1838, followed 
up Dufour’s observations, and named several new species, 
which he placed in four different genera—Clepsidrina, Rhiz- 
inia, Pyxinia, and Bullulina. There was, however, no ground 
for such a division, his genera being based upon the most 
trivial characters. 
Dr.C.Th.v. Siebold also, in the ‘ Neueste Schriften,’ Dantzig, 
1829, described new species of Gregarinze, which are given in 
the list below. 
In 1845, Kolliker* described several unilocular forms of 
Gregarine, from the intestines of various Annelida. Between 
the publication of this first paper of Kolker and _ his 
second, three German authors wrote, viz., J. Henle, in 
Miiller’s ‘ Archiv,’ 1845, who described, for the first time, a 
species of Gregarina from the earthworm; A. von Frant- 
zius (‘Observationes queedam de Gregarinis,’ Berolini, 1846), 
who, with Henle, questions the correctness of Kolliker’s 
assertion, that the Gregarinz are unicellular animals; and 
thirdly, Dr. F. Stein, in Miiller’s ‘ Archiv,’ 1848, described 
various new species of Gregarinz, and divided them into 
three families, of which mention will be made further on. 
KO6lliker then published his second paper in the first volume of 
Siebold and Kélliker’s ‘ Zeitschrift.’ He enumerates thirty- 
five species of Gregarinz, and enters at some length into 
their structure and affinities. The conclusions which he 
arrived at have before been quoted in these pages; it will 
be, therefore, only necessary to give them here briefly. Ist. 
The Gregarinz are animals. 2ndly. They consist indubitably 
* «Zeitschrift fiir wissenschaftliche Botanik,’ von M. T. Schleiden und 
C. Nageli, 2tes Heft, 1845. 
