168 Transactions of the Royal Microscopical Society. 
There were, as I have already said, many specimens of various 
sizes ; and the variations in size were so great that I had little 
doubt that they represented considerable variations in age, and that 
it was in consequence most probable that Cephalosiphon was a 
genuine Melicertan forming its tube from early youth, and not a 
temporarily encased Philodine. 
I searched therefore all over the weed in the hope of finding an 
infant Cephalosiphon ; and I was not unrewarded. Close to a large 
cluster of the tubes of Archimedea remex (a new infusorion, to he 
described lower down) was a very tiny tube, barely the of an 
inch long, and out of which protruded a wheel-animal (Fig. 1 , c ) 
Plate CXVII., about 2 I 0 °f an inch in length, and like a Cephalo- 
siphon only with a hump instead of the characteristic antenna. I 
isolated the creature and kept it under daily observation for nearly 
a fortnight, and during that time had the pleasure of seeing it 
grow rapidly into the form of an adult Cephalosiphon (Fig. 1 , cZ). 
In twenty-four hours the hump had developed into a short 
antenna ; in four days the young Cephalosiphon had grown from 
5^0 of an inch to ; in six days to -dt ; in twelve days to -fs- 
I was too busy to look at it during the next two or three days, 
and when I did find the leisure the creature was gone — tube and 
all. It was perfectly healthy on the twelfth day, and about half 
grown. This conclusively shows that Cephalosiphon is not an 
encased Philodine — even if there were no other reasons to be 
brought forward. 
Since I made the above observations I lighted on a reference to 
papers of Mr. Gosse and Mr. Slack on Cephalosiphon in the ‘ Intel- 
lectual Observer,’ vol. i., 1862. I have read these papers care- 
fully, and can quite confirm Mr. Slack’s statement that the trochal 
disk is not bi-lobed with a tendency to further division. It is, as 
he says, nearly circular with a deep notch in front of the antenna. 
Mr. Slack too is quite right in saying that the antenna carries 
setae at its extremity. It is clear that Mr. Gosse’s specimens (sent 
to him by Mr. Slack) were not in perfect health, and did not, in 
consequence, give that admirable observer a fair chance. He him- 
self says that his specimens “ were chary of exposing their facial 
charms,” and that his “ delineation of the form of the disk rests on 
a single individual.” 
No doubt the rotifers had suffered in their journey ; for 
when they are fresh from their pond they expand their disks 
freely. 
I have omitted to state that after numerous trials I succeeded 
in getting nearly the whole of a full-grown specimen out of its 
tube ; I could not see the extremity of the foot, but on the part 
which I did see — quite seven-eighths of the whole — there was no 
trace of any segmentation, nor of a telescopic joint, nor of any 
