OF THE MANDUCATORY ORGANS IN THE CLASS ROTIFERA. 
421 
In 1851 I published a catalogue of 108 species that I had observed, including 
descriptions of five new genera and thirty-two new species*. In this latter year 
M. d’Udekem published in the ^Memoirs of the Brussels Academy’ two papers -f', 
the one on the circulatory system in Lacinularia socialis, the other on Floscularia 
cornuta-, the latter as if a new species, but which had been described and figured by 
Dr. Dobie four years before. 
The former of these animals, Lacinularia socialis, became the subject of two very 
valuable papers in the year 1852; the one by Mr. Huxley j:, and the other by 
Dr. Leydig In the following year appeared a Memoir on the Anatomy of Meli- 
certa ringens," by Professor Williamson |1, closely followed by a second^ on the same 
species, by myself. 
7. In this enumeration I believe I have included all that has been published on the 
subject of the Rotifeba, from original observation : should anything, however, have 
been omitted, it is because it has eluded my most careful scrutiny. 
8. What changes may have been produced on the state of our knowledge of the 
nervous, vascular, glandular, muscular and reproductive systems of the Rotifera, 
by these researches, it is not my province here to inquire. My present business is 
with the digestive system, and particularly with the organs of manducation ; and of 
these, I think it is no more than the truth to say, our knowledge is almost exactly 
where Ehrenberg placed it five-and-twenty years ago. 
9. This assertion seems strange after so many memoirs, of more or less value, by 
different observers, on various species ; but the wonder is much lessened by a re- 
examination of their subjects. Of the thirteen monographs enumerated, two are on 
Floscularia, three on Melicerta, three on Lacinularia, three on Asplanchna, and two 
on Notommata. Now in Melicerta and Lacinularia the manducatory apparatus is of 
the same type, and that an abnormal one ; in Floscularia and Asplanchna the types of 
structure differ widely from the former, and as greatly from each other. These three 
types are in fact unintelligible in themselves, and can be explained only by tracing 
the organs from their normal development, through their modifications and degene- 
rations. Nothing then, in fact, has been attempted towards an explanation of the 
jaws, in the great families of Hydatinoea, Fuchlanidota, and Brachionoea — -the true 
types of Rotifera — except my own two memoirs on Notommata in 1850. And I 
freely confess, that, in spite of many and persevering efforts, I had not, at that time, 
been able to attain any satisfaction on the true structure of these organs. 
10. Nothing is easier than to see the forms of the various parts, in outline, in some 
one aspect; to obtain, for example, a dorsal or ventral view of the jaws in Brachio- 
* Ann. Nat. Hist. Sept. 1851. f Bull, de I’Acad. Belg. xviii. pp. 39, 43. I Journ. Micr. Soc. i. (Trans.) p. 1. 
§ SiEB. et Koll. Zeitschr., Feb. 1852. || Journ. Micr. Soc. i. (Comm.) p. 1. 
^ Ibid. p. 71. Note. — Since the presentation of this paper to the Royal Society, there has appeared in the 
‘Journal of Microscopical Science’ an abstract of another memoir by Dr. Leydig, “On the Structure and 
systematic Position of the Rotifera.” The original I have not yet had an opportunity of examining. — P. H. G. 
3 K 2 
