MAGltOTBACHELOUS OALLIDIN Jfi. 199 



euphemism to call these habitations tubes, but in the larger 

 examples there does appear to be an elastic tissue forming the 

 basis of the structure. Externally it is rough, as though coated 

 with and formed by particles brought together by the action of 

 the wheels. I have not, however, observed any movement of 

 the Rotifer suggestive of conscious tube-building, nor have I 

 seen the manner of the disposal of the faeces, which I have 

 thought might perhaps be the cause of the brownish colour of 

 the tube. Individuals without a sheltering tube are occasionally 

 seen nestling among the flocculent growth, but I believe that 

 these are either very young specimens or such as have been 

 recently disturbed or otherwise induced to leave their habita- 

 tions. Deserted tubes are not infrequent, but are usually small, 

 and often contain a single egg. 



My colony has existed for some three months, and, whilst the 

 increase in numbers has been slow, it has been maintained. Yet 

 it has been far outstripped by that of C. consfricta, a more 

 nomadic form, which has been its table companion in captivity. 

 This suggests that pusilla is less hardy, or is less prolific, or 

 that its eggs develop more slowly than those of its competitor, 

 whose eggs, indeed, are deposited wherever the parent may 

 happen to be, and left quite unprotected. The smaller size of 

 pusilla and its smaller trochal discs do not, I think, account for 

 the difference, for in the same trough I have several other larger 

 forms with spreading trochal discs, and none of these show any 

 increase at all. C. pusilla has one structural peculiarity 

 occurring in several other species, but not mentioned by any other 

 writer than Dr. Zelinka, who has noted its presence in C. 

 symbiotica. This is a peculiar hillock-like sw^elling upon the 

 dorsal surface of the first joint of the foot, arising apparently 

 from a local thickening of the hypodermis. Longer than broad, 

 and placed lengthwise to the body-axis and in the central line, 

 it is best seen in lateral view, when it appears as a low mound 

 rising gently in the front and extending nearly to the hinder 

 boundary of the joint, where it terminates rather abruptly. 



In the second new species the trochal discs have become 

 developed into two horn-like processes, which extend forwards, 

 and are so curved as to suggest at once the head of the male of 

 the stag beetle. I propose for it the name of cornigera. There 

 have been no forms discovered intermediate between this very 



