ROTIFERS. 451 



If. ringeiis, in each of which there is, according to Pro- 

 fessor Huxley, a double edge to the disc, of which the 

 subordinate one is placed on the under-side, and a little 

 within the line of the principle one. The former is fringed 

 with minute cilia, whose vibratile waves form well-marked 

 movements, which run evenly along the margin. The 

 eggs are usually laid within the case. 



To the genus MeUcerta Mr. H. Davis l adds one, if not 

 two, new species, which he has named, provisionally, M. 

 longicornis and M. intermedins. The two peculiarities of 

 these new forms are the remarkable length of the antennae, 

 and the construction of tube-dwellings for the purpose of 

 concealing themselves and their eggs. (Plate III. No. 

 69.) jEcistes longicornis : each animal lives in a separate 

 semi-transparent cylindrical sheath (urceolus), into which 

 it entirely withdraws on the approach of danger. The foot- 

 stalk is long, and firmly attached to the bottom of the tube. 

 Two or three ova are concealed in the lower part of the urce- 

 olus. The trocbal disc is large, and completely surrounded 

 by a ciliary wreath. The antennae, two, are very long, well 

 placed below the disc, and terminating in a small brush of 

 setae. The tube, Mr. Davis believes, is built up in the same 

 way as that of MeUcerta. 



Mr. Slack describes, in the " Intellectual Observer," 

 a tubicolous Rotifer, discovered in the stems of the Ana- 

 charis, which shows an affinity with JEcistes, Limnias, and 

 MeUcerta, but differs in some points, especially in the an- 

 tennae; this, named by Mr. Gosse Cephalosiphon, displays 

 a single antenna of extraordinary length and versatile 

 power. Like MeUcerta and Limnias, it shows no visible 

 construction below the disc, whereas in jEcistes this is a 

 conspicuous feature. 



" The animal inhabits a case slightly trumpet-shaped, 

 generally of greater length and slenderness compared with 

 those of its allies, standing erect on the pond-weed. It is 

 irregular and fioccose in outline, very opaque, and of a 

 deep umber brown by transmitted light, but of a much 

 lighter hue by reflected light. It is composed, doubtless, 

 vf an excretion from the skin as the foundation layer, 



(1) "On two new species of the genus JEcistes," by Henry Davis, F.RM.S. 

 Micros. Boo. Trans. April 1SG7. 



