WHEEL-BEAEEES. 275 



ductive of the more stationary animalcules, tlie Hoti- 

 fera especially. 



It was in this way I this morning found the pretty 

 and delicate little "Whiptail, which I am going to make 

 the subject of our evening's study. It is inclosed in a 

 glassy shell {J,orica) of a long oval form, from which 

 rises on the front half of the back a thin ridge which 

 ia the middle has a height nearly equal to half the 

 diameter of the body, but tapers oif at each end. Its 

 base is corrugated with wrinkles. This is not set on 

 symmetrically, but leans over considerably to the right 

 side. Its basal portion is hollow, and is continuous 

 with the general cavity of the shell, for we sometimes 

 see portions of the viscera in its interior. 



WHIPTAIL. 



The head of the animal is rounded, and divided 

 into several blunt eminences or lobes, which are set 

 with cilia ; these rotate constantly, but irregularly and 

 feebly, and do not make manifest wheels, as JBracJi- 

 ionus does. A small antenna projects from the back 

 of the head, capable of being erected or inclined. A 

 long brain descends along the base of the ridge, carry- 

 ing a bright and rather large crimson eye set like a wart 

 on its interior angle. 



Instead of the flexible and contractile foot of Brach- 

 ■ionus, the Whiptail has a single horny spine of great 

 slenderness, and exceeding in length the whole body. 



