68 THE ROTIFERA. 
ovary, add to the resemblance. The large head is bent downward; the brow and the 
chin project each in a sharp spine, between which the front is capable of a slight protru- 
sion, ciliated, and furnished with a tubular antenna. Viewed dorsally, the front is ever 
and anon closed by the rapid approach of two triangular pieces from the sides, which 
recede immediately (cf. Dinocharis, &c.). The movement has no connection with the 
mastax. When the animal is confined by pressure, not sufficient to hurt it, it protrudes 
the jaws ; and besides this a sort of veil is thrust forward, very thin and membranous, 
seemingly stretched between the frontal and mental points, and from an intermediate 
point (fig. 18)). The action, though frequent, is momentary, and the withdrawal is 
complete. The lorica terminates anteriorly by a strong transverse fold, at its full width, 
whence the mobile head is emitted, of much less apparent diameter. The difference, how- 
ever, 1s mainly owing to a rather high dorsal ridge, which rises abruptly from the fold, and 
continues nearly equal in height to three-fourths of the body’s length ; or even, in some 
cases, to the whole.!| The basal joint of the foot is a round transparent bulb of great 
size, almost wholly enclosed within the body-walls. It must not be confounded with the 
contractile vesicle, which is much smaller, and lies upon it. To this foot-bulb is so 
articulated as to allow very free vertical motion the remarkable form of toe which has 
been just described. It is usually bent forward toward the belly, but can be thrown out 
behind, particularly in swimming. The trophi resemble those of Mastigocerca: the 
fulcrum of the incus a long slender rod with the back elevated into a thin ridge; no 
trace of rami can be discerned, but their pendent divergent alulze, which are unequal. 
The whole mastax is covered with fine transverse lines. A wide and long brain, of the 
normal form and position, carries near its middle a great deep crimson eye. On killing 
one by sudden pressure, the branchial vessels were severed from their connection with the 
contractile vesicle, and forced out, displaying some details of their structure. They ap- 
peared as a single tubule on each side, striate in parts with cross lines; towards their 
hinder parts are seen a number of transverse branchlets, whose ends have been torn off, 
suggesting not one but many communications with the contractile vesicle. There are 
also very minute structures attached at intervals to them, one near the head, resembling 
a twig of several leaves. These I cannot explain. 
With this very attractive little creature I have been familiar since October 1849, 
when I met with it at Clapton, near London. It has occurred in many localities since. 
Its manners are sprightly and elegant. It is perpetually in motion, threading its way 
through the tangled conferva wires, and swimming across the open spaces, with a rapid 
gliding movement, turning on its long axis asit goes. The clear viscera, resembling 
bladders of various shapes and sizes, some filled with richly-coloured food or feces, 
others granulate, or occupied with embryonic globules, all interspersed with orange- 
coloured fat-bubbles, and all seen through the transparent skin, have a most charming 
effect, as the animal thus revolves. It frequently arrests its roving course to examine 
the plants, and now and then to nibble at them, when the mastax is brought to the very 
front, and the jaws themselves are seen projecting from the head, and eagerly biting. 
Sometimes it swims round and round, in a circle of which the curyed outline of the back 
forms an are.—P.H.G.] 
Length, ,1, inch, of which the double toe forms about one-fifth. Habitat. Pools 
and lakes ; widespread through Middle and South England (P.H.G.). 
C. TENUIOR, Gosse, sp. nov. 
(Pl. XX. fig. 19.) 
(SP. CH. Body cylindric, decurved, slender ; lorica without sensible ridge ; head 
defended by two or three projecting points ; toe with two sub-styles. 
1/T am almost sure that the ridge is inclined ; its edge bending over towards the right. I have seen 
it distinctly wrinkled along the base, as seen in MV. carinata.—P.H.G. 
