468 GENERAL HISTORY OF THE INFrSORIA. 



end, and others had none : I thought at first that these threads were some 

 mucus from within, escaped thi'ough some opening which might have served 

 the Rotifer as an entrance ; but an attentive and lengthened observation con- 

 vinced me that in this there was no solution of continuity, and that the arrival 

 of the Rotifers in the Vaucherice was not at all to be explained in this way. 

 How are these parasitic animalcules generated within them ? This is what 

 further research has some day to show. Meanwhile I have thought that it 

 should be made known that the animalcule foimd in the Vauclierice by linger 

 was the Rotifer vulgaris of zoologists." 



Several of the Philodincea, and particularly the CaUiclince, have been met 

 with in snow, along with the so-called red snow, in very cold regions, and 

 at considerable elevations, such as above the pei'petual snow-line of the 

 Alps. Perty informs us that mosses and lichens collected in the Swiss 

 mountains, at a height of 9000 feet, have yielded, on wasliing with distilled 

 water, numerous Infusoria, including several Rotatoria, ^4z. CalUdina ele- 

 gans, Rotifer vulgaris, Philodina roseola, DigJena catellina, and Ratidus 

 lunaris. 



We have no data whereon to construct laws of geographical distribution 

 for the Rotatoria. Obseiwation has proved no definite regional limitation of 

 species ; wherever searched for, the same species seem discoverable. 



Owing to the perishable natru'e of theii^ tissues, the Rotifera do not occui- 

 in a fossil state ; they are, moreover, rare components of the showers of In- 

 fusorial dust. 



Of the Affinities and Classification of the Rotatoria. — That the 

 Rotatoria, by their high degree of organization, should be elevated in the 

 animal scale far above Protozoa, is now universally admitted. Indeed they 

 cannot be rightly comprehended among Infusoria if this term be accepted to 

 indicate a definite class of beings ; for although there are slight general re- 

 semblances between some Rotatoria and Protozoa, no true near affinities of 

 structure exist between them. 



A\Tiile naturalists generally are in accord on this necessaiy separation of 

 Rotatoria from Protozoa, they are much at variance respecting the relative 

 position of the Rotatoria in a classification of the Invertebrata, or, in other 

 words, concerning the true affinities of the class. Thus Burmeister, Owen, 

 Lej'dig, Dana, and Gosse would range them among Cinistacea as a particular 

 order; whilst Wiegmann, Milne-Edwards, Wagner, Siebold, Cohn, Perty, 

 Williamson, Huxley, and others would class them with Vermes — a section 

 comprehending Helmmthae, Tiu-bellaria, and Annelida. 



We shall first state the argiunents used to demonstrate the Crustacean 

 alliance, which are most fully and powerfully brought forv\'ard by Leydig ; 

 they are, that 



'' The external figure is rather that of Crustacea than that of Yeinnes. 

 None of the latter have a jointed organ of motion, such as most Rotifera 

 possess in their annulated or jointed pseudopodium devoid of aU viscera. 



'< The shield-like hardened integ-ument or lorica of some species, such as 

 Euchlanis and Salpina, has its analogue among the Cmstacea, M'hilst in none 

 of the Vermes is a similar indurated cuticle to be foimd. 



''Vermes are destitute of striated muscles; but Rotifera, equally with 

 Cmstacea, possess them. The movements of many species recall in a striking 

 manner those of Crustaceans. The nervous system supphes fiu'ther evidence ; 

 for although the Rotatoria have no pharyngeal ganglionic ring and no chain 

 of abdominal ganglia proceeding from it, yet a similar deficiency prevails with 

 the Lophyropoda and the Daphnice, recognized Crustaceans, which have only 

 a cerebral ganglion and radiating nerves like the Rotifera ; consequently it 



