ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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the horse, the ass. and the mule, and is not, as has been stated, entirely 
harmless, for infected horses are subject to periodic attacks of great 
restlessness and excitability. The body in the adult female consists of 
an anterior curved and thickened region and a posterior slender region ; 
it varies in length from 29 mm. to 185 mm. In the much smaller male 
the body is rounded and slender, and the total length does not exceed 
15 mm. Experiment showed that horses could be directly infected with 
the worm by drinking water containing embryos obtained from an adult 
female. The following are the most striking anatomical peculiarities. 
In the female the anus is at the end of the thickened region of the body, 
so that the thin tail does not contain any part of the gut. This tail- 
region, however, contains two lateral canals, which begin behind the anus 
and extend throughout the whole length. They are probably connected 
with the excretory canals, but the existence of such a connection was not 
proved. At the junction of the buccal cavity and oesophagus, the lining 
cuticle is thickened to form three projecting plates, which are fringed 
with a sieve of bristles. From the centre of the bristles in each plate a 
funnel-shaped tube projects, which close examination shows to be the 
orifice of one of the three oesophageal glands. In connection with the 
female organs there is a very curious “ onion-shaped organ ” of unknown 
significance, which connects the vagina with the exterior. The paper is 
illustrated by some exceedingly clear figures. 
Platyhelminthes. 
New Turbellarian.* — Herr H. Sabussow describes Bdhmigia mans - 
albi g. et sp. n., an acoelous Turbellarian from the White Sea. Having 
a single genital opening, it belongs to the Proporidse, but differs from 
Proporus in having a bursa seminalis , and from other genera of the 
family : — (1) by the absence of eye-pigment ; (2) by the position of the 
testis in the lateral parts of the body ; (3) by the absence of a tunica 
. propria on the testis ; (4) by the absence of vasa deferential and (5) by 
the simpler structure of the penis. 
Development of Convoluta.f — M. Jivoin Georgevitch has studied the 
development in C. roscoffensis Graff. The eggs are usually laid in groups 
of five to twelve, and are surrounded by a transparent investment.. The 
egg divides completely to produce two equal blastomeres. At the four- 
cell stage two upper cells (ectoderm) are distinguished from two lower 
larger cells (endoderm). The endoderm cells, after an interval of repose, 
divide laterally, giving rise to two cells which are the origin of the 
mesoderm. The ectoderm cells also divide, and the resulting eight cells 
constitute the blastula. Gastrulation is chiefly by epibole, but there is 
no central cavity. The central parenchyma of the adult arises from the 
endoderm, the peripheral from the mesoderm, which also gives rise to 
the muscles and genital organs. After the formation of the gastrula, the 
ectoderm becomes clothed with cilia, and the embryos escape from the 
capsule. They do not contain zoochlorellse, and only obtain these when 
the surrounding water contains adults. Unless zoochlorellae be obtained, 
the embryos seem to die as soon as their reserves are exhausted. 
* Zool. Anzeig., xxii. (1899) pp. 189-93. 
f Comptes Rendus, cxxviii. (1899) pp. 455-7. 
