OF THE PFILODIXiEA. 701 



The nutritive apparatus consists of an oesophageal bulb, with two jaws ; in 

 three of Ehi'enberg's genera these are double-toothed (Zygogomphia) ; in two 

 the teeth are in rows (Lochogomphia), In the four principal genera the ali- 

 mentary canal is filiform ; it is furnished -^dth a bladder-like expansion at its 

 commencement (Trachelocystea), and surrounded by a turbid cellular or glan- 

 dular mass. In one genus the alimentary canal is conical (Coelogastrica), in 

 the two African genera its character is unknown. In four genera the intes- 

 tine has glands ; in a like number an ovary and glands are present ; a con- 

 tractile vesicle exists only in Rotifer and Philodina, which, together with 

 Actinurus, are also sometimes vi\iparous. In Rotifer and Philodina, portions 

 of a muscular system are visible, in the form of from nine to twelve trans- 

 verse bands ; the same genera, as also Actinurus and Monolahis, have spur- 

 like tactile tubes. In thirteen species red eyes are present; and beneath 

 these organs, only what is supposed to be nervous matter is apparent. 



For Ehrenberg's arrangement of the genera, see General History, p. 479. 



" The characters employed," says Dujardin, " by M. Ehrenberg, for the 

 distinction of his genera of Philodincea, have certainly too slight a constancy 

 to be admitted ; that author has himself seen the red specks, which he calls 

 eyes, vary in number and position in his Rotifers. As to the appendages of 

 the tail (toes), they are not always alike visible, although actually present, 

 because the animal does not extend them except at certain moments ; the 

 central terminal appendage — that by which the Eotifers affix themselves to 

 solid bodies — is itself of greater or less length, but always present. "We 

 therefore think that but two genera can be rightly established : one, CaUidinaf 

 characterized by the feeble development of its ciliated rotary organ, and by 

 entirely wanting red specks; the other, Rotifer, with two or several red 

 points placed more or less near the exterior extremity, and, what is of more 

 importance, T\ith very highly developed rotary organs." 



" The genera Hydrias and Typhlina are foimded on imperfect observations 

 made by the author during his journey in Egypt ; and the genus Monolahis 

 ought to be placed elsewhere." 



The family Philodinaea thus fonned is arranged parallel with Erachionsea, 

 as though the absence of a lorica were the only difference between them. 



So far as Dujardin accepts of the same species, his family Eotifera and that 

 of Philodinaea of Ehrenberg correspond. 



The amazing persistence of vitahty in the Rotifer vulgaris gives a great 

 interest to this family, as also the occurrence of some of its members 

 within the cells of aquatic plants. Dr. Morren's observations probably ex- 

 plain some of the latter occurrences; but it is a question whether recent 

 discoveries in vegetable physiology may not further explain the existence 

 of these animals ^vathin closed vegetable sacs. For instance, the origin of 

 some cells by the vacuolation of a soft penetrable protoplasm suggests the 

 possibility that the Rotifera may deposit their eggs within the soft, half- 

 organized protoplasm ; and in the process of vacuolation some of these ova 

 might readily find their way into the vacuoles about to be converted into 

 cells, the latter change being completed before the embryonic animalcule 

 escaped from its ovum ; and when it did so emerge, the completion of the 

 vegetable process would cause the animal to find itself imprisoned within the 

 waUs of a vegetable cell. 



Genus CALLIDIjS^'A (XXXIY. 470-473).— Distinguished by possessing a 

 proboscis, and a foot furnished with processes resembling horns, and by the 

 absence of eyes. The vibratile or rotary organ, is double, not pedicled, and 

 is surmounted \)j a thickly ciliated proboscis. The furcate foot has two 



