G8 THE KOTIFEEA. 



ovary, arid to tlie resemblance. The large head is bent downward ; the brow and tlic 

 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. IHb). 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, is 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 tropin resemble those of Mantigocerca : 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 alulse, 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 

 contractUe 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 1840, 

 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 as it goes. The clear viscera, resembling 

 bladders of various shapes and sizes, some filled with richly-coloured food or fieces, 

 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 curved outline of the back 

 forms an arc. — P.H.G.] 



Length, yj-o inch, of which the double toe forms about one-fifth. Habitat. Pools 

 and lakes : widespread through Middle and South England (P.H.G.). 



C. TENuiOE, Gosse, sp. nov. 

 (PI. XX. fig. 10.) 



[SP. CH. Body cylindric, dccurved, slender ; lorica witliout sensible ridge; head 

 defended by tivo or three projecting j^oints ; toe ivitk two sub-styles. 



' I am almost sure that the ridge is incHned ; its edge bending over towards the right. I have seen 

 it distinctly wrinkled along the base, as seen in M. carinata. — P.H.G. 



