MICROSCOPIC FORMS OF ANIMAL LIFE. 



63 



a muscular pharynx, into a wide alimentary canal, which gradually nar- 

 rows to the anus. There are no special organs of circulation or respira- 

 tion, but the nervous system is much more developed than in the Roti- 

 fera; a cerebral mass, bearing two eyes, giving origin to two longitudinal 

 cords, on which are seated 

 pairs of ganglia in connec- 

 tion with the members, as 

 in Articulated animals 

 erally. Their nearest ai 



FIG. 313. 



Noteus quadricomis: A, dorsal view; B, side view. 



jen- 



ini- 



ties seem with the lowest 

 forms of the Arachnida. 



454. Notwithstanding 

 that all the best-informed 

 Zoologists are now agreed in 

 ranking the true Rotifera 

 among Articulated animals, 

 yet there is still a consider- 

 able discordance of opinion 

 as to the precise part of that 

 series in which they should 

 stand. Prof. Leydig, who 

 has devoted much attention 

 to the study of the class, 

 regards them as most allied 

 to the Crustacea, and terms 

 them ( Cilio-crustaceans; ' 

 and the curious Entomos- 



tracan-looking Pedalion of Dr. Hudson might seem a link with that 

 group. 1 Prof. Huxley, on the other hand, has argued that they are 

 more connected with the Annelida, through the resemblance which they 

 bear to the early larval forms of that class ( 595); while in their single 

 bilobed nerve-ganglion and water-vascular system, they seem allied to 

 Planaria ( 593). 2 



1 See Prof. E. Ray Lankester's 'Remarks on Pedalion^ in "Quart. Journ. 

 Microsc. Sci.," Vol. xii. (1878), p. 338. 



2 The following Treatises and Memoirs (in addition to those already referred 

 to) contain valuable information in regard to the life-history of Animalcules and 

 their principal forms: Ehrenberg, "Die Infusionsthierchen, ' Berlin, 1838; Du- 

 jardin, "Histoire Naturelle des Zoophytes Infusoires," Paris, 1841; Pritchard, 

 " History of Infusoria," 4th Ed., London, 1861 (a comprehensive repertory of in- 

 formation); Stein, " Der Organismus der Infusionsthiere," Leipzig, Erste Abthei- 

 lung, 1859, Zweite Abtheilung, 1867, Dritte Abtheilung, Halfte i., 1878: Saville 

 Kent's "Manual of the Infusoria," 1880-1; and Prof. Biitschli's Pro tozoa (1880, 

 1881) in the new edition of " Bronn's Thierreich." For the RHIZOPODA and IN- 

 FUSORIA specially, see Claparede and Lachmann, " Etudes sur les Infusoires et les 

 Rhizopodes," Geneva, 1858-1861; Cohn, in " Siebold and Kolliker's Zeitschrift," 

 1851-4, and 1857; Lieberkuhn, in "Miiller's Archiv," 1856, and " Ann. of Nat. 

 Hist.," 3d Ser., Vol. xviii., 1856; Engellmann, " Zur Naturgeschichte der Infusions- 

 Thiere" (1862); and Prof. Butschli's " Studien fiber die Conjugation der Infuso- 

 rien," etc., 1876. For the ROTIFERA specially, see Leydig, in " Siebold and Kolli- 

 ker's Zeitschrift," Bd. vi., 1854; Gosse on Melicerta ringens, in " Quart. Journ. of 

 Microsc. Science," Vol. i. (1853), p. 1; Huxley on Lacinularia socialis in "Trans- 

 act, of Microsc. Soc.," Ser. 2, Vol. i. (1853), p. 1; and Cohn, in " Siebold and Kolli- 

 ker's Zeitschrift," Bde. vii., ix. (1856, 1858). Mr. Slack's " Marvels of Pond Life " 

 (2d Edit., London, 1871) contains many interesting observations on the habits of 

 Infusoria and Rotifera. 



