OF THE Hi'DATIXJEA. 681 



a cordate internal muscle, and foiu' im- I during contraction, shows four muscular 

 equal bristles. Amongst Confervse, &c. . sheaths; and the distinct red eye is placed 

 1-120". upon a less distinct ganglion; the oeso- 



Mastigocerca carinata is regarded by phageal head is not evident. 1-288". 

 Perty and Dujardin as identical with M. hrachyura (Gosse). — Form that of 

 Monocerca Rattus. Dujardin identifies iJf. i2«if/'«/s, but the foot short (one-fourth 

 AA-ith this an animal he discovered and of total length), slightly curved, and 

 figured (xxxviii. 22), measuring 0*147 ' horizontally flattened ; a large eye in the 

 niillim., or with its tail 0-29 millim. j occiput, and another small one in the 



M. bicornis. — Ovate, oblong, trimcated breast. Length, including foot, 1-185". 

 in front, armed with two spines ; foot M. Porcellus. — Thick and plump ; foot 

 styliform, a little shorter than the body ; short, much curved and bent imder the 

 the oblique oesophageal head exhibits body, dilated, flattened liorizontally, and 

 delicate transverse corrugations ; it has carrying a smaller spine beneath it as in 

 a bent and a straight jaw, \\dth probably ! a sheath ; front and chin each armed 

 three teeth in each, (xxxiii. 399, an | with a short shai-p spine. Length, in- 

 animal seen on its right side ; 417 an- \ eluding foot, 1-110". 

 other, contracted, and having its rat- j M. stylata. — Short, iiTegiilarly oval ; 

 like tail bent.) 1-72". I foot a nearly straight spine, less than 



M. (?) xalcia ( Vorticella valf/a, M.). — i one-third of total length ; eje large, red, 

 Small, almost cubical, ^\ath distinct head, set like a wart on the back of the occi- 

 au elevation on the back, and a conical j pital sac ; forehead conical, pointed, 

 foot unequally forked ; the rotaiy organ, i Length, including foot, 1-170". 



Genus XOTOM^^IATA (XXXIII. 416-421 ; XXXYI. 3-6 ; XXXYII. 

 27-32 ; XXXYIII.26 ; XXXIX. 8, 9).— These have, according to Ehrenberg, 

 a single eye upon the neck, and a bisulcate foot, resembling a forked tail. 

 The rotary organ compound, its cilia forming bundles on the frontal region. 

 Eight of the larger species have numerous muscles. Of Ehrenberg's species 

 eighteen or nineteen have two jaws, each furnished with a single tooth ; in 

 eight the jaws have many teeth. The oesophagus is mostly short, with a 

 simple wide conical alimentary canal (Coelogastrica) ; in N. tuba only is there 

 a stomach-like division, mth a constriction (Gasterodela) ; and in N. Myr- 

 meleo, N. Syrinx, and N. davidata there is also a stomach-like enlarged 

 place, but no constriction (Gasterodela) : caecal appendages are observed only 

 in N. davulata. The two ear-like anterior appendages of the alimentary 

 canal, regarded by Ehrenberg as pancreatic glands, exist in twenty-fom- 

 species. N. Syrinx alone was observed by Ehrenberg to contain fully- 

 developed ova. The water-vascular system is represented in ten species by 

 delicate tubes, with flexible and tremulous gills ; only three of the smaller 

 species have gills. In iV. Myrmeleo and N. Syiinx a broad vascular network 

 is distinct about the head. A prominent tactile tube in the neck is present 

 in four or five species ; in some others an opening alone is seen. The visual 

 point is red, except in N. Felis, where it is colourless ; a ganglion is placed 

 beneath the eye in twenty-six species. In A^. Copeus and N. centrura the 

 brain (?) is three-lobed, and placed over the oesophageal head ; in the rest it 

 consists of one or more nervous ganglia, situated amongst the ciliary muscles 

 of the frontal region. This genus is especially remarkable for the parasitical 

 habits of its members. They live upon other Rotatoria, upon the Polygastrie 

 Infusoria, and even within the globular masses of Volvox Globator ; " but," 

 says Ehrenberg, '' not like a cuckoo's eg^ in a hedgesparrow's nest, but like 

 the bear and the bee-hive, or a bird's nest in a wasp's nest." 



Dujardin has the following criticisms on this genus : — " Five of the species 

 appear to be Hydatince; nine others, more or less distinct, are, in our opinion, 

 Fiircidarice ; three others PJagiognatlii ; some are imperfectly known ; and 

 only six, at most, ofiPer suiRciently precise characters to retain the name 

 Eotommata. Such are, 1. N. copeus, 2. N. centrura, 3. N. brach/ota, 4. N. 



