616 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
The author retains the name ootyp for the organ in which the germ 
is enveloped by yolk-globules and enclosed in a solid shell. It varies 
in form and structure. From it there passes off a wide canal which 
becomes united with the pouch of the penis to form the genital cloaca ; 
this is the oviduct. It is very short in Monocotylids, where it serves 
only for the expulsion of the eggs, but in the others it is very long and 
capable of dilatation, so as to preserve the eggs for some time ; hence 
the name of uterus, which some authors have given it. 
The vitellogenous apparatus is always well developed, and situated 
in the lateral parts of the body ; its follicles are bounded by an extremely 
delicate membrane, and have no epithelial layer. The small ducts given 
off from the follicles unite into two long longitudinal canals, capable 
of being enlarged on necessity. In no form of the group has the author 
found any duct analogous to the vitello-intestinal canal which has 
been described in a number of Polystomidse. In all, however, there is 
a seminal reservoir or receptacle in which the spermatozoa are stored 
before being used. It is always a pouch of some size which communi- 
cates with the female ducts by an extremely narrow canal. A vagina is 
found in some forms only, and it may be single or double. The double 
form is probably the more primitive, and the single one is due to the 
disappearance of either the right or the left member of the pair. 
Water- vascular System of Mesostomum truncatum.* — Dr. W. 
Yoigt finds that this Turbellarian is more capable than most, of 
resisting the pressure of the cover-glass, and he has been able to 
follow out the whole course of its water-vascular system. The two 
efferent orifices do not open into the outermost portion of the pha- 
ryngeal pouch, but further back, and freely on the ventral surface of 
the worm. A line of connection between the two orifices passes 
about midway between the mouth and genital orifice. There is no 
terminal piece running transversely through the body, but, as in 
Derostomwn unipunctatum, there is a vascular trunk on either side, 
which passes forwards with looped coils, bends round just behind the 
eyes, and, getting gradually narrower, may be followed to the hinder end 
of the body. A few ciliated funnels were observed in the first and last 
thirds of the body. The author proposes to form a new genus for this 
worm on account of the abnormal position of the excretory orifices, which 
he calls Olisthanella. 
Monostomata from Intestine of Chelone viridis.t — Herr E. Walter 
records from this tortoise AmpMstomum scleroporum Crepl, Monostomum 
trigonocephalum Rud., M. reticular e Van Ben., and M. proteus Brandes. 
He has studied in the last of these the mode of termination of the dorso- 
ventral musculature. It has hitherto been supposed that the muscles 
of the parenchyme were inserted on the inner surface of the limiting 
membrane ; he finds, however, that, in M. proteus , they traverse the 
whole of the membrane ; this last is perforated by pore-canaliculi, 
through which diverging fibrils of muscle pass. Similar relations have 
also been observed in other Trematodes. 
M. reticulare is to be found in such different forms that, were inter- 
mediate stages wanting, it would be easy to make a new species. In 
* Zool. Anzeig., xv. (1892) pp. 247 and 8. f Tom. cit-, pp. 248-50. 
