274 EVENINGS AT THE MICROSCOPE 



The most remarkable circumstance connected with this 

 elegant little animal is the unusual form of the dental ap- 

 paratus, which differs so immensely from that of Brack- 

 ionus that we should never recognize them as being 

 the same organs, if we had not numerous intermediate 

 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 ir- 

 regularly 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 an- 

 gles greatly produced. The mallei have long, slender, 

 incurved manubria, and simple unci. 



But the remarkable circumstance is the non-symmet- 

 rical 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 dilated into an expansion, with several 

 irregular 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, com- 

 bined with the unsymmetrical character of the dorsal ridge, 

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

 genus ft highly curious one to the naturalist. 



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



