OF THE MANDUCATORY ORGANS IN THE CLASS ROTIFERA. 
449 
both are very distinet ; the labriim being furnished with stiff arched setae, the labium 
plain, but bifid (§ 94). 
147 . I am not aware that any trace exists, in the Rotifera, of any organs, or pro- 
cesses, answering to palpi, either labial or maxillary. I was at first disposed to con- 
sider the processes at the bases of the rami, which f have called alulae (§ 47), as 
maxillary palpi ; but, as muscle-bands, in many cases, are inserted into their 
points, it is manifest that they will not bear this character. 
148. To sum up these observations — we may consider a perfect mouth in the 
Rotifera as consisting of seven elements; viz. a lahrum, a pair of mallei, a pair of 
incus-rami, a fulcrum, and a labium ; corresponding homologically to the lahrum, the 
mandibles, the maxillae (with their cardines), and the labium, of Insects. 
149. But, if this parallel be truly drawn, it is interesting to trace the same organs 
to their extreme point of degradation, and to mark where they disappear. Their 
minimum of development is attained in Floscularia, and Stephanoceros, which (not- 
withstanding the opinion of Mr. Huxley* to the contrary) do certainly lead to the 
PoLYzoA. The latter, therefore, present the point where the two great divisions of 
the Animal Kingdom, the Mollusca and the Articulata, unite, in their course 
towards the true Polypes. 
150. Now, in one genus of Polyzoa, there is a structure, which we may com- 
pare with the apparatus in Rotifera. The oval muscular bulbs in Bowerbankia 
densa, which approach and recede in their action on food, as described by Dr. Arthur 
Farre, in his admirable memoir on the Ciliobrachiate Polypi 'j-, appear to me to 
represent the quadranti globular masses of Limnias, Rotifer, and Stephanoceros, 
reduced to a lower condition of structure, and deprived of mallei. 
151. I do not see that this conclusion in the least involves (as Mr. Huxley sup- 
poses) the denial of either the Molluscous affinities of the Polyzoa, or the relation- 
ship of the Rotifera with the Vermes ; the latter being clearly approached by another 
road, through the Annelida. It would be easy to show (were this the suitable 
occasion for it) that the Rotifera link with the latter, through Taphrocampa and 
Chaetonotus; as they do with the Entozoa, through Albertia. 
* Journ. Mic. Sci. i. (Trans.) p. 16. t Philosophical Transactions, 1837, p. 392. 
