74 THE ROTIFEBA. 



was about -j 1- - inch long ; but, owing doubtless to its having just been hatched, the skin 

 was so granular and corrugated that I could not make out its whole structure. The 

 nervous ganglion, sperm-sac (ss), and penis (p], were plainly visible, and I could 

 see the motion of the spermatozoa, though not the individual spermatozoa themselves : 

 neither could I make out the muscles nor the water vascular system. I did not see 

 this creature hatched ; still, as there were no other Kotifera present but M, ring ens and 

 M. tyro, it was certainly the male of one or the other. 



The Eotiferon, I have little doubt, is Ehrenberg's Tubicolaria Naias. He formed 

 the genus to receive a Melicertan that was destitute of eyes at all periods of its life, 

 and lived in a gelatinous tube. But Ehrenberg points out that he has not seen the 

 young, and that therefore the absence of eyes cannot be depended upon as a charac- 

 teristic. His other characters of the genus are, a four-lobed corona, two antennas, and 

 a gelatinous tube. Of these, the latter alone is peculiar to Tubicolaria, and as it is not 

 sufficient to found a genus on, I have placed the animal among the Mclicertce. 1 



Length. Adults from about ^ to -J s inch ; the maximum size given is that of Scotch 

 specimens. Habitat. Ponds and ditches, Birmingham (C.T.H.) ; Chartham, Kent (Col. 

 Horsley) ; Forfar ( J.H.) ; Heading (Tatem) : rare. 



M. JANUS, Hudson. 



(PI. VII. fig. 1.) 

 CEcistes Janus .... Hudson, J. Roy. After. Soc. 2 Ser. vol. i. 1881, p. 1, pi. i. 



Upper lobes deeply divided, lower nearly confluent ; dorsal gap minute; antennae 

 short; chin two-pointed ; pellets fcecal. 



This remarkable Rotiferon is one of those creatures whose form is as irritating to 

 the classifier as it is delightful to the naturalist. For it possesses in almost equal pro- 

 portions the characteristics of two genera, viz. of Mcliccrta and of CEcistes, and might, 

 with nearly equal propriety, be placed in either genus. It was found first by Mr. J. 

 Hood in Loch Lundie in 1880, and was most numerous, and in best condition, on weeds 

 at a depth varying from six to ten feet. 



When seen from the ventral surface, so that the lower lobes are partly hidden by its 

 tube, no one would suppose it other than a Melicerta; but when it turns and exhibits its 

 dorsal surface, it is seen that the lower portion of the corona resembles that of CEcistes, 

 for, instead of there being a wide dorsal gap in the ciliary wreath, there is scarcely any 

 at all (PI. VII. fig. 1) ; and the subdivision of the lower portion of the corona is so 

 slight that the outline of its two lobes is almost confluent : in fact, it might almost be 

 said that this is a three-lobed Melicertan. As in CEcistes, thickenings (fig. Id) cross 

 the corona, which itself is so thin that it becomes nearly invisible under dark-field 

 illumination, while the thicker portions stand out distinctly, especially when seen side- 

 wise (fig. 16). When the animal begins to open its corona, these portions are thrust 

 forward in a squarish and very characteristic bundle, the thinner parts of the disk lying 

 folded neatly between them. In this respect M. Janus closely resembles CEcistes 

 umbclla. 



The cilia of the corona are unusually large, while the groove that lies between the 

 principal and secondary wreaths is broad and deep. Should the larger cilia be checked 

 by contact with the side of the cell in which the animal is placed, it is easy to count 

 them, and their whip-like action becomes plainly visible. Individual cilia may now and 

 then be seen even in the secondary wreath. 



The chin (fig. Ib, ch) is also peculiar. It terminates, not in one point, but in two 



1 It must be admitted that Ehrenberg's figure is very unlike mine. The corona is barely the width 

 of the body, and the antennae are very short ; but I think that both disk and antennae are intended to 

 be represented in a contracted state. 



