52 
On the occurrence of the Rhizopod, 
was first found by Cienkowsky near St. Petersburg on water- 
plants ( Xitel!a and Vaucheria ), and was described by him, in 
1867, in Scliultze’s ‘Archiv fur Mikroskopische Anatomie.’ 
It was also found by Haeckel near Jena, and by Greef near 
Bonn; and the form was subsequently detected by Mr. W. 
Archer in the Callery-bog near Bray, and in Co. Tipperary, 
Ireland; also in Wales; and by Dr. Leidy in N. America. 
Mr. Archer at first described it (not being aware of Cien- 
kowsky’s discovery) under the name of Podospliceria haeckel- 
liana (Quart. Journ. Micros. Soc. viii. (1868) 67). It was 
always found very sparingly; but Mr. Archer was disposed 
to think that its distribution would be found to be pretty 
wide, although perhaps rare in individuals, and restricted to 
isolated spots. The structure of Olathrulina seems to show 
that it is a protozoon allied to the fresh-water Heliozoa (of 
which Actinophrys sol may be taken as an example), and 
connecting that well-known form with the marine Kadiolaria 
(the Polycistina of Ehrenberg). It is an exquisitely beautiful 
object, the protoplasmic body-mass being contained in a 
superb latticed globe of silica, reminding one of the carved 
ivory balls cut by the skilfully-patient hands of the Chinese 
artisans. Figures of it in its various stages will be found in 
Dr. Leidy’s magnificent work, ‘ The Fresh-water Rhizopods 
of North America,’ forming volume xii. of the United States 
Geological Survey of the Territories (1879). The peduncle 
by which it is attached to its point of support is very flexible 
and of varying length ; and in mature individuals, according 
to Leidy, the homogeneous granular protoplasmic body 
occupies only the centre of the globular capsule, leaving a 
space between it and the circumferential walls. Thread-like 
prolongations of the protoplasm are extruded through the 
foramina of the capsules, subserving the prehension of food, 
in the manner so frequently witnessed by microscopists in 
the case of the common Actinophrys of our ditches and ponds. 
Reproduction appears to take place in four ways :—(a) By 
fission, as observed by Cienkowsky—the protoplasmic body 
dividing into two (rarely four) simple granular spheres which 
pass out of the silicious capsule, and subsequently develop 
each a stem, and still later a foraminated capsule of its own. 
(0) By the throwing off of small sarcode bodies, as apparently 
observed by Mr. Thomas and described above in his notes, 
which subsequently pass through an Actinophrys- like stage, 
and then secrete the characteristic silicious capsules, (y) 
Hertwig and Lesser describe (Archiv. fur Mik. Anat. 1874) a 
third mode in which the body-mass breaks up into a number 
of smaller masses, each of which becomes surrounded by an 
