43S 
PROCEEDINGS OF THE SOCIETY. 
for its chitinous lorica, a specimen of which he had brought for exhibi- 
tion, the creature itself not being easy to exhibit, in consequence of its 
rapid movements. Claparede mentioned its having been found at 
Berlin ; hut hitherto it had only seemed to be found in sea-water. 
Prof. Bell said they had received another communication from 
Mr. T. B. Rosseter, who had for some time been interesting himself 
in endeavouring to trace out the life-history of certain tape-worms. It 
would be remembered that some months ago he had sent a paper on the 
subject, but it was then shown that his observation had been anticipated. 
He had now sent a paper describing the development of Taenia lanceolata 
from the duck, the cysticercoid form of which had not been previously 
known. He appeared to have fed the ducks with some of the Cypris 
known to be infested with the parasite, and after some weeks opened the 
ducks and found the tape-worms mentioned. It was, of course, interest- 
ing to get the life-history of another tape-worm worked out. 
Mr. T.B. Rosseter has prepared the following abstract : — He reports the 
discovery of a new Cysticercus which makes Cypris cinerea its intermediate 
host. The peculiarity of this Cysticercus consists in the fact that when 
evaginated from the cyst by the action of reagents the four suckers on 
the scolex are seen to be armed with from 180 to 200 very minute hooks ; 
their measurement, individually, is 1/5000 in. from base of anterior 
root to tip of claw. These hooks are arranged around the periphery of 
the suckers and again longitudinally from the polar axis to the base of 
sucker in rows of three hooks in each row, and their position on the 
sucker is in reverse order to the hooks on the rostellum. The rostrum, 
which is invaginated in the cysticercus stage, bears ten hooks, each one 
measuring 1/600 in. Ducks when fed with this Cysticercus produce a 
tape-worm similar in every respect to the embryonic scolex in the cyst, 
even the minute hooks on the suckers existing in this stage of the life- 
history of the creature. This armature of the suckers is unique in the 
history of cysticercoids and Cestoida. The hooks on the rostellum, the 
rostrum itself, the elongated proboscis, scolex, and generative organs all 
correspond to the Taenia lanceolata of Goeze, Rudolphi, and Dujardin. 
No mention is made by any of these investigators of the existence of 
hooks on the suckers of this tape-worm. Such being the case, Cysticercus 
with ten hooks and armed suckers (Rosseter) equals Taenia lanceolata 
(Goeze, Rudolphi, Dujardin). 
Mr. E. M. Nelson read a note on the subject of “ Lateral Develop- 
ment in Photography,” advanced by Mr. Pringle in his note printed in 
the Journal of the Society for April last, pp. 263-4. He had tried 
many experiments, leading to the conclusion that Mr. Pringle was wholly 
mistaken in supposing that the width of a flagellum is increased to an 
extent at least 50 per cent, by lateral development. If lateral develop- 
ment of this kind occurred, it would eat into the image of the flagellum 
on the negative, and so make it thinner than the image on the screen ; 
but when the negative was printed this lateral development would act in 
the opposite direction, and if the actions were equal in extent the size of 
the flagellum would be restored to the original size of the image on the 
screen. In no case could the action of the lateral development on the 
