B4 THE ROTIFERA. 
from the circumstances, I dare not vouch for the minute details, particularly of the 
incus-rami. The respiratory organs, in the form of slender cords, loosely twisted 
together, but, as I presume, tubular, can be traced to the very front of the head; at 
least to the point on each side where the proximity of the brain to the integument 
allows them to be no longer discerned; and thence backward without interruption, till 
their ends ramify and are lost on the walls of the ample contractile vesicle that occupies 
the termination of the abdominal cavity. It was an operation of much delicacy, but 
with a }-in. obj. I think I satisfactorily followed the entire course described. In the 
ample abdomen the viscera are large. The alimentary canal is clearly separated into a 
stomach and an intestine. In all the individuals examined, neither of these held any 
visible food, but both were tinged with pale umber-brown. An ovary of embryonic 
vesicles, and a great dark ripening ovum, were conspicuous in one. At the expansion 
of the long cesophagus into the stomach are the pair of ovate colourless glands, which 
possibly are biliary, and may impart the prevalent yellow-brown tinge to the digestive 
canal. The dorsum, just before the point where it contracts into the foot, rises into an 
angular prominence ; which must be regarded as a true tail, because beneath and behind 
it is the common excrementary outlet, whether for matters urinary or feecal—the cloaca. 
The anterior side of the orifice is crowned with a bristled tubercle (fig. 5d), very closely 
resembling that projecting from the hind head. It seems a tubular wart with a thick- 
ened rim, bearing a rather short seta on the summit. From the base of this are 
discerned, clearly running down through the transparent tube, two fine lines, which 
probably are the optical expression of a nervous cord, bending forward to some sensible 
distance up the body, till lost behind the viscera. I searched (vainly) for some ganglion 
in the vicinity, with which this thread may communicate. But I rather presume that 
it runs through the body, and communicates with the great brain at the very front. It 
seemed to me that each of these tentacular warts, both that on the head and that on 
the tail, is susceptible of sensible elongation, and of occasional withdrawal, partial or 
perfect. The foot is slender and colourless, like the anterior parts, and is terminated by 
two minute and delicate toes; from which two long, club-shaped muscles pass forward 
nearly to the cloaca. 
The species was discovered by Dr. Collins in 1865, in a small pool near Sandhurst 
Military College, whence he has recently sent me a supply. There seemed here the 
exercise of a sense of companionship, at least in captivity. After some days this species 
became rather numerous in the bottle of water-moss, and I have had, perhaps, a dozen 
in my live-box at once, of various ages. I noticed, much too often to be merely 
fortuitous, that they were in the habit of associating in couples, two beimg generally in 
close contiguity, and now and then coming into actual contact; the one crawling, in 
their lithe embracing manner, over the foreparts of the other; separating, however, 
immediately after. It was not sexual. In young individuals, not more than half as 
long as the adult, all the characters are developed; except the great length and almost 
invisibility of the neck, which are not so manifest.—P.H.G.] 
Length, ;4, inch. Habitat. Sandhurst, Berks (Collins); Dundee (P.H.G.). 
C. Cerserus, Gosse, sp. nov. 
(Pl. XVI. fig. 3.) 
Notommata centruva. Gosse (nec Khr.), Ann. Nat. Hist. 2 Ser. vol. viii. 1851, p. 200. 
(SP. CH. Tentacles wholly wanting (or unobserved) ; auricles small; brain three- 
lobed ; tail a minute tubercle. 
This species approaches the ordinary Notommate, in form and in the absence of 
those projected organs of sense which characterise the other species of this genus. 
Yet the general aspect, the sluggish manners, and the three-lobed brain, seem to war- 
