ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
479 
of a white or nearly white colour. Some thirty are enclosed together 
in a sausage-shaped mass of colourless transparent jelly ; this jelly 
appears to be common to all the eggs and does not, as in the case of 
frog-spawn, form a special envelope round each. The eggs probably 
leave the body separately by the narrow duct which serves also for the 
admission of the spermatozoa. The author thinks the jelly is a secretion 
from the surface of the body. 
British Marine Turbellaria.* — Mr. F. W. Gamble finds that at 
present there are known as members of the British fauna fourteen Poly- 
clads, two Triclads, and fifty-five Bhabdocoels ; these he describes, giving 
the distinctive structural and bionomical points. It is, however, to be 
noted that these numbers represent the examination of a limited extent 
of the English coast, the Channel Islands, and the Isle of Man during 
three months of summer (July to September). The author has increased 
the number of British species by twenty-eight, of which Provortex rubro - 
bacillus , Plagiostoma pseudomaculatum , P. elongatum , and Automolus 
Jiorridus are new species. The faunistic relations of our Turbellaria 
cannot yet be certainly determined, but it is clear that a large proportion 
of Scandinavian forms occur, and 33 per cent, are common to Naples, 
Plymouth, and Trieste. In the investigation of the British Turbellaria 
there is obviously ample work for the students of minute forms. 
Cercaria of Amphistomum subclavatum.f — Dr. A. Lang has dis- 
covered that this well-known Trematode ( Diplodiscus subclavatus Dies.), 
not unfrequently found in the rectum of Amphibians, has Planorbis 
contortus (L.) Mull, for its intermediate host. No sporocysts were found, 
which suggests that the rediae (in summer at least) arise directly from 
the embryos. The Cercariae leave the snail by the rectum, swim about, 
attach themselves to the skin of amphibians and become encapsuled. 
It is likely that they are swallowed along with portions of cast skin. 
Experiment showed the efficiency of this mode of infection. 
The author also gives an account of the structure of the Cercaria, 
especially of the excretory system, which has not hitherto been described 
in detail. 
Anatomy of Caryophyllseus mutabilis-t — Kerr H. Will has made 
an investigation into the structure of this interesting Cestode. The 
absence of proglottids and the simplicity of the sexual apparatus are 
sufficient to show that it occupies an important position as a primitive 
form. But even here there are intermediate stages. Although it is 
true that the Ligulidae, when sexually mature, exhibit a formation of 
proglottids with a repetition of the parts of the sexual apparatus, yet it 
is doubtful whether isolation is carried as far as in the Bothrio- 
cephalidae, while the proglottis of the latter by no means attains the 
stage of individuality seen in Taeniae. 
In the nervous system, the two primary trunks which traverse the 
whole length of the animal, and are connected with one another a short 
way behind the head by a dorsal and a ventral transverse commissure, 
are common to it and other Cestodes. In addition there are dorsal and 
* Quart. Journ. Micr. Sci., xxxiv. (1893) pp. 433-528 (3 pis ). 
t Ber. Nat Gesell. Freiburg i. B., vi. (1892) pp. 81-9 (1 tig.), 
t Zeitsohr. f. wiss. Zool., lvi. (1893) pp. 1-39 (2 pis.). 
