40 Mr. R. Vallentin on the 



alteration, and terminate at tlie base of the corona or troelial 

 disk. 



Alimentary Canal. 



Melicerta rinqens and M. conifera. 

 (PI. iV. figs. 1-8.) 



All previous investigators have noticed a paired structure 

 visible above the mastax. It is found to be present in the 

 majority of Rotifers. Dr. Hudson (1) says concerning this struc- 

 ture in M. ringens as follows : — " On each side of the buccal 

 funnel and above the mastax is a clear organ whose surface is 

 spheroidal. The two have been described as salivary glands 

 by some observers, and as mere stays to the mastax by others. 

 They are obviously clastic, and move up and down with its 

 every motion." Although these paired structures are easily 

 distinguishable in the Rotifers included in the present paper, 

 I find their structure most easily deciphered in Melicerta 

 conifera. It is my intention to take this species as an illus- 

 tration and to describe the structure of these bodies as briefly 

 as possible. 



On reference to PI. IV. figs. 1 and 2, which are serial sections, 

 it will be noticed that, placed immediately above these "sphe- 

 roidal bodies," are certain glandular cells ; the protoplasm 

 being wanting in many instances, these cells were probably 

 in an active state of secretion at the death of the animal. 

 Attached to the inner wall of each " spheroidal body," or, as 

 I shall in future call it, salivary receptacle (for that is what I 

 take them to be), is a valvular body, which places the cavity 

 of each receptacle in immediate connexion with the gut 

 (fig. 2, a). It Avill also be noticed that there is a slight 

 deposit of secretion visible within each salivary receptacle. 

 Dr. Hudson noticed these valvular openings. He says, " It 

 [the buccal funnel] is ciliated throughout, and has a pair of 

 chitinous lips similar to those described at p. 6." The refer- 

 ence given refers to a lengthened description of these struc- 

 tures as they are found in Brochionus rnhens. Dr. Hudson 

 here says, *' But it is not every atom whirled down the buccal 

 funnel that is suflcrcd to reach the mastax ; for there are 

 two lip-like ])roccsscs rising from the mastax, which can be 

 seen every now and then thrust uj) and down the buccal 

 fuinicl ; and Aviiich by closing prevent the passage of morsels 

 that are not to the Rotiferon's taste." 



It seems to mc highly probable that Dr. Hudson has 

 slightly misplaced the ]ioint of attachment o'i these valvular 



