240 EVENINGS AT THE MICROSCOPE. 



inserted at some distance within the aperture of the 

 lorica. This articulation is formed by an infolding of 

 the skin, but is permanent in its position. 



The most remarkable circumstance connected with this 

 elegant little animal is the unusual form of the dental 

 apparatus, which differs so immensely from that of 

 Brachionus, that we should never recognise it as consist- 

 ing of the same organs, if we had not numerous inter- 

 mediate links, which by insensible gradations connect 

 the two remote forms. 



The mastax is a somewhat slender sac, much produced 

 in length, and with the component lobes greatly and 

 irregularly developed. The incus has a fulcrum of great 

 length and slenderness, a straight rod with a dilated 

 foot. The rami are small, and pincer-shaped, but with 

 the angles greatly produced. The mallei have long, 

 slender, incurved manubria, and simple unci. 



But the remarkable circumstance is the unsymmetrical 

 character of the apparatus. The left side is much more 

 developed than the right. The left angle of the incus 

 descends to a greater distance than the right ; and its 

 extremity is spread out into a surface with several irre- 

 gular points, to which muscular threads are attached. 

 The ramus also of the same side is larger than its fellow; 

 so with the mallei. The manubrium of the right is com- 

 paratively short, very slender, and of uniform thickness; 

 with a long, slender, rod-like uncus, doubly bent in the 

 middle. The left is much longer, irregularly swollen, 

 clubbed at the articulation, and bearing a thick, curved, 

 knotted uncus, which terminates at a point not precisely 

 opposite the tip of its fellow. These circumstances, 

 combined with the unsymmetrical character of the dorsal 

 ridge, of the foot-spine, and of some other organs, render 

 this genus a highly curious one to the naturalist. 



The little Whiptail is as lively in its motions as it is 

 elegant in its form. When swimming, it glides with con- 



