NOTE ON (ECISTES PILULA. 303 



position of the marginal wreath of setas and the cingulum or 

 secondary belt of ciha and of the ganglion, relatively to a hne or axis 

 drawn from the mouth to the anus. Of these two families he proposed 

 to make Melicertidse include the genera Mehcerta, GScistes, Limnias, and 

 Tubicolaria under the term Melicei-ta, while Conochilus, Lacinularia, 

 and Megalotrocha were to be grouped together under the common name 

 of Lacinularia. 



But later observers have added several species to each of the old 

 genera, the characters of which are sufficiently distinct to justify the 

 retention of the older divisions. The difference of the form of the disc 

 is a sufficient distinction between Mehcerta on the one hand and Limnias 

 and CEcistes on the other, while the two latter are separated by the 

 different form of the lobes, the character of the theca, and their general 

 habit. 



If we accept the genus fficistes at all, the species we are now 

 describing should certainly be included in it. My friend. Dr. C. T. 

 Hudson, says on this point — " They are fficistes, and good specimens of 

 the genus." 



Mr. Cubitt's description of the singular habit of this animal is quite 

 correct, but he does not appear to have obsei-ved the precise manner in 

 which the remarkable operation is performed, from which it derives its 

 name. It is self-evident that only a minority of the excrementary pellets 

 discharged by the creattu-e can be required or used to fortify its theca. 

 The larger part are whirled away from the vicinity of the animal in 

 the manner familiar to all who have observed the thecated Rotifers or 

 the freshwater Polyzoa — but those which are utilised for building 

 purposes are ejected between the rotifer and its tube or theca, and 

 received under the lower margin of the cihated trochus, where they 

 remain for a few seconds as if the animal were making sure of its proper 

 hold, and then by a sudden retraction of its body it dabs the pellet into 

 a proper position on the margin of the theca, and instantly resumes its 

 usual condition. The amount and regularity of the pellets with which 

 the tube is fortified varies very much. One finds occasionally an 

 individual in which they are so few and irregular as only to suffice for the 

 identification of the species. Regular feeding -with water containing 

 abundant food produces a corresponding increase in their number and 

 regularity, and a supply of carmine and indigo on alternate days is 

 followed by the deposition of very regiilar alternate layers of red and 

 blue courses on the outside of the tube, which, when viewed by strong 

 dark background illumination, then forms a very pretty object. 



My specimens produced abundant ova, which were formed in the 

 usual manner in the ovary, and thence extruded into the space between 

 the animal and its theca, and deposited upon the lower part of the foot, 

 as is customary with this division of the Eotifera. I have not yet 

 observed their development nor, although I have examined a large 

 number of specimens, have I yet been fortunate enough to see the male 

 of this species. 



A. W. Wills. 



