HISTOKY OF LITERATURE CONCEENING THE ROTIFEEA. 21 



His criticisms are shrewd and often just ; he points out that Ehrenberg's respiratory 

 tube is probably an antenna ; suggests that the convoluted tubes, flickering tags, and 

 contractile vesicle of the vascular system have a respiratory function ; calls atten- 

 tion to the varying forms of the mastax and trophi as good characters for classification ; 

 and conjectures that the perivisceral fluid is the true analogue of the blood. 



On the other hand, he could not see Floscularia' 's tube ; could not make out the 

 striated muscles in any Eotiferon, even in Pterodina patina, of which he gives a figure ; 

 could see indeed no difference between the muscles and the nerves ; doubted the exist- 

 ence, as specialised structure, of either the one or the other ; and from want of personal 

 acquaintance with them, affirmed the identity of many of Ehrenberg's species, which 

 are undoubtedly distinct. 



But although he has small claim to be considered either an original or an accurate 

 observer of the Eotifera, he made one happy hit in his attempted classification, which 

 will be detailed elsewhere. 



Since Dujardin's time the more noteworthy essays that have been published on 

 various portions of our present subject are by Mr. P. H. Gosse, F.E.S. ; Dr. F. Leydig ; 

 Professor T. H. Huxley; Herr C. Vogt ; Dr. F. Cohn; Dr. W. Moxon, F.L.S. ; 

 Dr. W. Salensky ; Dr. S. Bartsch ; and Herr Karl Eckstein. 



Mr. GOSSE, in his paper, " On the Anatomy of Notommata aurita," l described with 

 minuteness the organization of this common species, so that the essay became, as it 

 were, a key to the structure of the majority of free-swimming Eotifers. His next treatise, 

 " On the Structure, Functions, and Homologies of the Manducatory Organs in the Class 

 Eotifera," 2 is illustrated with a great many drawings of the mastax and trophi of various 

 species ; and discusses the changes that they undergo, in passing from the typical to the 

 most aberrant forms. It is in this treatise that Mr. Gosse contends that the dental 

 organs of the Eotifera are true mandibulae and maxillae ; and that the mastax is a mouth ; 

 and assigns to the Class a position among the Articulata. In a subsequent paper, " On 

 the Dicecious Character of the Eotifera," 3 Mr. Gosse extended this character from a single 

 genus, Asplanchna, to five others ; and trebled the number of the known dioecious species. 

 Some years later, Mr. Gosse began, in " Contributions to the History of the Eotifera," 4 

 a general account of the whole class, arranged according to a classification of his own, 

 and continued it so far as the Flosculariadce, Melicertadce, and Notommatina, illus- 

 trating each family with descriptions and figures of certain selected species. This work, 

 however, owing to the cessation of the periodical, was never completed. 



Dr. F. LEYDIG, in " Ueber den Bau und die systematische Stellung der Eaderthiere," 5 

 after a full description, accompanied with figures, of many species, three of which are 

 new, proceeds to deal with the structure of the Eotifera as a class, and to arrange them 

 in a system of his own. He further discusses their true position in the animal kingdom, 

 and assigns them a place among the Crustacea. 



Professor HUXLEY, in his paper, " On Lacinularia socialis ; a Contribution to the 

 Anatomy and Physiology of the Eotifera," 6 takes this Eotiferon as his text, and, while 

 minutely describing its structure, discusses various questions concerning that of the 

 whole class. He enters into the general relations of the Eotifera to other animals, and 

 arrives at the conclusion that they are permanent forms of Echinoderm larvae. 



Herr C. VOGT, in his treatise, " Eiiiige Worte iiber die systematische Stellung der 

 Eaderthierchen," 7 combats Leydig's reasonings and conclusion oil the position of the 

 Eotifera, and affirms that they must be classed among the Vermes. 



In Dr. F. COHN's essay, "Ueber die Fortpflanzung der Eaderthiere," 8 the males 

 and females of three species are minutely described, especially with reference to their 

 reproductive organs ; and the general question of the reproductive system of the whole 

 class is also discussed. 



Dr. W. MOXON's 'Notes on some Points in the Anatomy of the Eotatoria" 9 call 



1 Trans. Micr. Soc. 1852. 2 Phil. Trans. 1856. 3 Phil. Trans. 1857. 



4 Popular Sci. Rev. 1862 and 1863. 5 Leipzig, 1854. 6 Trans. Micr. Soc. 1853. 



7 Sieb. u. Koll. Zcits. 1855. 8 Sieb. u. Roll. Zcits. 1856. Trans. Linn. Soc. 1864. 



