70 THE ROTIFEEA. 



Limnias ccralojihijlli . . Tatcm, J. Qttcketl Micr. Club, vol. i. 1808, p. 121, 



\}\. vi. figs. 1, 2. 

 Limnias socialis .... LciJy, Proc. Acad. Nat. Sci. Pa. 1874, p. HO. 

 Liinnias ceratoj)h>jUi . . ■ BedwoU, Mon. Micr. J. vol. xviii. 1877, p. 221, pi. 



cxcviii. figs. 7, 8. 



SP. CH. No horny processes on the dorsal surface below the corona ; ventral antennae 

 very short; tube nearly cylindrical, smooth, often rendered opaque by e.ctrancous 

 viaterials, except at the posterior end. 



I have already related, in Chapter I., Leuwenhoek's discovery of this the earliest 

 known tube-maker. It has not been much studied, as its tube is often quite opaque, and 

 its own attractions have been eclipsed by those of Melicerta. The tube is of a yellow- 

 brown tint and is generally coated over on the outside with waste nuitter tliat falls 

 down on it from the coronal currents above, and with the particles that trickle over the 

 diin, and aiUiere to the sticky surface beneath it. These latter are rubbed off from time 

 to time on to the tube by the animal, as it bends its head over it. Doubtless this 

 renders tlie tube smooth and compact. Judge 15edwell {loc. cit.} thinks that there 

 is a cliitinous shield below the dorsal gap, whose hard edge is shown at xz, fig. Id. 

 lie points out that its position corresponds to those of the horuy processes of L. annulatus, 

 and the sharp hooks of M. ringens ; and he suggests that the tube is smoothed with it 

 "much as a bricklayer smooths over his stucco with his flat trowel." The tube is 

 generally not coated towards its posterior extremity, and is very imperfectly covered in 

 tlie young (fig. Ig). Occasionally adults are met with that have tolerably transparent 

 tubes,' and even large adults have sometimes tubes of an opaque white (fig. lb). 



Ehrenberg recognises no vascular system,- but Dr. Moxon (loc. cit.) has observed 

 part of it, and given a figure of the neck and expanded corona, with two vibratile 

 tags on the same side. I have had no difficulty in seeing the lateral canals, and 

 their accompanying tags, in the upper portion of their course, from a vascular plexus 

 near the shoulder, up to a similar one in the corona (fig. 1/, Ic, vt). The contractile 

 ve.-icle (if there is one) has not yet been noticed. 



Desides the two short ventral antennae (PI. VI. figs. Id, If, a) Dr. Jloxon (loc. cit.) has 

 observed a minute dorsal one similarly situated to that in 21. riiujens. 



Prof. Leidy (loc. cit.) says that in many localities of the Schuylkill, almost every 

 stone exhibits multitudes of bunches of a Limnias, pendent from its sides, and under 

 surface : as many as fifty tubes may be counted in a bunch. Prof. Leidy proposes to 

 call this rotifer L. socialis, on account of its habit of growing in clusters ; but as the 

 auinuil itself is said to be like L. ceralophyUi in other respects, and as L. ccratophylli 

 in England has this habit of clustering to a considerable degree ^ it is. unnecessary to 

 make a new species of the American Eotiferon. 



Male. [As a Limnias was slowly protruding from its tube, there swiftly pushed 

 past it, out of the mouth of the tube, a young one, which I supposed from its general 

 appearance, a male.'' It was a simple cylinder of colourless flesh, slightly tapering be- 

 hind to a blunt point, with no foot or tail apparent, of about one-third of the total 

 length of the parent, filled with miinite globules of oil or air. There was a simple 

 crown of cilia around the truncate front, a well-sized and well-made mastax, an enor- 

 mous blunt-pointed brain-sac reaching about two-thirds do-vn its total length, and 

 carrying, on its dorsal side, near its point, a small but clear round eye-spot of crimson 

 hue. Its manners were those common to males, swimming swiftly around the parent, 

 often coining close to her for a moment, and then darting finally ofl' on a wide wild 

 voj'iige. Tliat tliis was truly a male individual of the species is highly probable, not- 

 witlistanding the presence of a mastax, of which there was no doubt, and of a long 

 viscus below wliich appeared to be a stomach. P.II.G.] 



Length. ^laximum about J- inch. Habitat. On water plants : very common. 



' Mr. Gossc (loc. cil.), p. 303. - " Kicmnii uiul Gcfiisse siiul niclU ciUanut.'' 



' Hcc p. 38 ; n. VI. lig. Ic. ' PI. D. fig. 7. 



