196 
Cricetomys gambianum 
mentioned. There is a tendency for the eggs in the uterus to become isolated 
each in separate cavities, and as the proglottis matures this process continues 
until all the eggs lie in a single dorso-ventral row, each in its own egg-capsule 
formed from the walls of the disappearing uterus (PI. IX,fig. 5). These capsules 
become aggregated together in groups of 9-11 and surrounded by a fibrous, 
rather spongy modification of the body parenchyma; this forms a distinct 
sheath round each group and also penetrates in between the individual cap¬ 
sules. Each group of eggs thus becomes completely separated from its neigh¬ 
bours (PI. IX, fig. 6). In a transverse section there are approximately 16 
of these capsules, extending on both sides past the excretory vessels and 
nearly reaching the nerve: dorso-ventrally they occupy nearly all the space 
between the two opposite layers of transverse muscle. 
Between these capsules there is still left a certain amount of medullary 
parenchyma, but as growth proceeds this completely disappears, the egg- 
capsules, becoming polygonal by compression, occupy all the space bounded 
by the transverse muscles and form a double dorso-ventral layer instead of a 
single one (PI. IX,fig. 7). Each capsule has now a definite delimiting membrane 
externally and consists of two portions: an outer fibrous spongy mass, and an 
inner granular non-nucleated matrix in which are imbedded the eggs. I could 
not find any traces of the second layer figured by Baylis (1915, fig. 6). In 
each proglottis, now approximately square, are 40-50 egg-capsules each con¬ 
taining 9-11 eggs and filling all the space between the two longitudinal 
nerves in one direction and between the anterior and posterior margins of the 
proglottis in the other. 
The possession of an unarmed scolex and the absence of a persistent 
uterus place this worm in the sub-family Linstowinae Fuhrmann 1907. This 
includes up to the present six genera, two of which, Linstowia Zschokke 1898 
and Oochoristica Liihe 1898, are definitely separated from the form under 
discussion by the position of the female organs in the median portion of the 
proglottis. The third genus, Hyracotaenia Beddard 1912, by the absence of a 
persistent uterus (a character which should remove the genus from this sub¬ 
family) can therefore be dismissed. The other three genera, Inermicapsifer 
v. Janicki 1910, Zschokkeella Fuhrmann 1902 and Thysanotaenia Beddard 
1911 are closely allied and, up to the present, insufficiently separated from 
each other. 
The only characters distinguishing Thysanotaenia appear to be the poor 
development of the excretory system, the more median position of the female 
organs and the larger size of the cirrus-sac. The variability of the excretory 
system is often very great in allied species; in Oochoristica crassiceps Baylis 
(1920, p. 293) found no excretory plexus nor any transverse commissures; on 
the other hand in O. wagneri v. Janicki the excretory system is well developed. 
Rudin (1917, p. 317) states: “Ganz ausserordentlich sind die verschiedenen 
Formen der Ausbildung, die das Excretionssystem, nicht nur innerhalb der 
Genera Ophiotaenia und Acanthotaenia, sondern im allgemeinen innerhalb der 
