OF THE MANDUCATORY ORGANS IN THE CLASS ROTIFERA. 441 
lodged in a little conglobate cellular mass Professor Williamson denies that the 
transverse teeth move on the plates, as affirmed by Ehrenberg, since they are firmly 
united with them. He further states, that “ the conglobate organ in which the appa- 
ratus is imbedded [?‘. e. the mastax~\ is composed of numerous large cells, each of 
which contains a beautiful nucleus with its nucleolus and supposes that muscular 
threads penetrate it to reach the dental apparatus ■f-. The statement of the cellular 
character of the mastax, and the presumption of penetrating muscles, are alike nega- 
tived by my observations, not only of this species, but of the whole range of the Ro- 
TiFERA. The able and learned Professor has probably been misled, in the former 
conclusion, by some overlying tissues, perhaps similar to the salivary glands in 
Euchlanis (see § 48). 
105. My own observations on the same species, published in the same journal, did 
not succeed in dispelling the obscurity which still rested on the structure ; and I shall 
therefore here merely allude to them, as a part of the bibliography of the subject. It 
appears, however, that though more attention has been bestowed on this type than on 
any other in the class, it still needs solution. I shall therefore attempt to give it in 
detail, as it appears in Limnias ceratophyUi (Plate XVIII. figs. 66 to 71)- 
106. The mastax consists (fig. 66, a) of three subglobose lobes, as usual (not four, 
as stated by Leydig, and by Ehrenberg before him); one on each side appropriated 
to each malleus {h), and the third descending towards the ventral aspect, which 
envelopes the incus {f). The mallei are more intimately united to the rami of the 
incus than in the former type ; each uncus forming, with its ramus, a well-defined 
mass of muscle, enclosing the solid parts, and in form approaching the quadrature of 
a globe (^); two flat faces opposing and working on each other (fig. 66). Across 
the upper surface of the mass the uncus is stretched (fig. 71 ) o), as three long parallel 
fingers, arched in their common direction, and imbedded in the muscular substance ; 
their points just reaching the opposing face of the ramus, and meeting the points of 
the opposite uncus, when closed. The manubrium (c) is much disguised, by being 
greatly dilated transversely, forming three bow-like loops of little solidity, to the 
chord of which the fingers are soldered, not articulated. The surface of the dense 
muscular mass displays striae parallel to the fingers, and, as it were, continuing their 
number towards the dorsal extremity, becoming fainter till they are imperceptible. 
These strice do not disappear when the muscular parts are dissolved by potash ; and 
hence I infer the existence of a delicate investiture of solid substance, similar to that 
of the teeth, &c., enclosing the muscular mass. 
107 . The incus, which cannot be separated from the mallei, thus consists of two 
portions (g), corresponding to the rami in Brachionus, &c., each of which forms the 
* These two prolongations are, as I conceive, but the lateral outlines of the fulcrum ; and the joint is not 
at the point where they unite, as Professor Williamson supposes, but at the point of their widest separation, 
whence the rami diverge. 
t Journ. Micr. Sci. i. (Comm.) p. 4. 
