On Cephalosiphon, &c. By Dr. C. T. Hudson. 167 
‘ Popular Science Beview,’ vol. i. p. 490) that he had found two 
specimens of a fine wheel-animal without a tube, and which he had 
reason to think was Ptygura. “ One of the animals,” says Mr. 
Gosse, “ laid a large egg actually under my eye, so that it was in 
adult age. Its general figure was somewhat trumpet-shaped, 
slightly swelling in the middle The disk was very large, forming 
a nearly circular outline, and partially surrounded by a layer of 
granular tissue. The foot terminated in an adhering sucker, whose 
figure resembled that of a glass stopper in a phial ; the dilated ex- 
tremity of this was capable of adhering to any foreign substance.” 
The specimen I found at Nailsea — unluckily a solitary one — 
tallied very closely with this description ; but it was very awkwardly 
placed, half bent round a leaf, so that I could only get occasional 
glimpses of the body and head, while of the foot I could see but 
little. I satisfied myself however that it had no case, though I was 
not quite sure whether there was not a sort of fluffy gathering at 
the foot. The foot too was thicker than it is in other Melicertans, 
and more coarsely wrinkled. 
For the present, at all events, I am afraid that Ptygura must 
be retained as a Melicertan that does not make a tube. 
I was more fortunate with Cephalosiphon. There were many 
specimens on the weed, and of various sizes ; and the very first I 
looked at was a half-grown one protruding sufficiently from its 
tube to show that it had a smooth, jointless foot, precisely like that 
of a Melicertan, but quite unlike that of a Philodine. 
The trochal disk was oval, with a gap in it on the side opposite 
to the mouth. Two parallel rows , of cilia — the upper large, the 
lower small — ran round the edge of the disk separated by a groove 
which led down into the mouth (Fig. 1, a); and the lower row of 
cilia were continued round the edges of the mouth after the usual 
fashion in Melicertans. But what struck the eye at once was the 
long flexible antenna. When the creature was withdrawn into 
its tube the antenna generally projected above it like a thin wand. 
It was turned too to a curious use; for when Cephalosiphon 
had made up its mind to emerge from its retreat, it hooked its 
antenna (see Fig. 1, b) over the side of its tube, and getting a 
good purchase, hoisted up its body into a great curve, and then 
letting go its grip of the case, unbent itself, and at once unfolded 
its disk. The antenna bore on its end a brush of diverging 
setae, and was often not quite straight. It was attached to the 
animal in an unusual way, for it had a broad base something like 
that of the thorn of a rose, as if its great length required extra 
support. I am not aware that there is any Melicertan that at all 
resembles Cephalosiphon in these two particulars — that is to say, 
that makes so odd a use of its antenna, or that has its antenna 
broadening out into a bracket-like base. 
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