622 Transactions of the Society. 



in ending posteriorly in a blunt rounded cone curving up towards 

 the dorsal surface. 



These humps are mere prolongations of the thin cuticle, and both 

 the dorsal and lateral ones are only fully extended when the creature 

 withdraws its head into the folds of the body. Each time that it 

 does this the three humps are seen to fly out to a great length, 

 making the animal from one point of view look like an equilateral 

 triangle, and from another like a pyramid. The humps are quite 

 empty, save that delicate muscular threads pass from their apices 

 to various parts of the body. The dorsal hump of the male has as 

 many as tour of these, while one fine fibre actually passes right 

 through the centre of the body from the apex of one lateral hump 

 to that of the other. When either the male or female is swimming 

 quietly, the lateral humps lie empty, wrinkled, and inconspicuous 

 on the surface of the body ; and the dorsal hump has only half its 

 possible elevation. Behind the latter the cuticle lies in a multi- 

 tude of concentric wrinkles encircling its base, so as to hinder the 

 distinct view of the organs beneath ; they can however be easily 

 seen through the ventral surface. The male has two cuticular 

 processes that are lacking in the female. These lie on the ventral 

 surface beneath the neck, and are smaller than the other three. I 

 did not detect any muscular threads in them, and they do not seem 

 to fill and empty as the others do. The whole range of the Eotifera 

 does not contain a more curious or more beautifully transparent 

 creature than this male. Though often l-30th of an inch in size, 

 and but a slow swimmer, it is scarcely perceptible to the naked 

 eye; and through the Microscope it looks like a many-pointed 

 bubble of blown glass. 



The female also is very transparent, and is a still slower swim- 

 mer. It is fond of grubbing at the bottom of the live-trough 

 among the sediment ; and it every now and then contracts the cir- 

 cumference of its wide trochal disk, and lashes more vigorously with 

 its cilia, so as to drive some tempting morsel towards its mouth. 

 It is almost colourless, with the exceptions of the eye and stomach ; 

 the former a very dark crimson, and the latter a yellow ochre. 

 Occasionally the ovary is also tinged with the same yellow about 

 its middle, and I have seen the ephippial eggs of the same tint. 

 The animal feeds on other rotifers, whatever else it may eat, for 

 I have seen Brachionus angularis still alive in its stomach, the 

 victim's ciha and jaws yet feebly moving. But A. Ehheshornii is 

 not particular as to what rotifer it catches. In the stomach of 

 one I detected the jaws of one of its own species, and on watching 

 the animal I saw these jaws rejected, through the mouth, with 

 other undigested food. It was a curious sight. The long, thin 

 oesophagus, with the stomach (fig. 9), was drawn up towards the 

 pharynx (fig. 14), and at the same time shortened and widened so 



