34 SCIENCE SKETCHES. 



starts and buries his head and neck in the now 

 whirling sand, by a motion as quick as thought; 

 his tail beats frantically about, and when again the 

 clean sand lies smooth on the bottom, the little eyes 

 are looking at you like two glistening beads, as if 

 to witness your applause at so clever a trick. 



We have never seen Ammocrypta taste of food, 

 nor do we ever expect to do so ; for although its 

 mouth bristles with teeth, its small size forbids an 

 attack on any game which we can offer. Its qui- 

 escent habits and the character of the bottoms to 

 which it confines itself seem to indicate that its 

 prey is minute if not microscopic. But speculation 

 about what we do not know as to its food might 

 lead us to speculation as to the origin of its char- 

 acteristic features, how, for instance, the hard 

 snout, the transparent muscles, and the burrowing 

 habits are consequent on its loss of scales, or how 

 the loss of unnecessary scales and of pigment cells 

 is consequent on its burrowing habits. Then, 

 when we have finished these matters, we might 

 inquire how it came about that there are "Johnny 

 Darters" at all, and why no other continent has 

 them. And we might go on with endless queries 

 like these, which would take us far beyond the 

 purpose of this article. We have wished only to 

 introduce our aquarium friends, and to commend 

 them to all lovers of beautiful things in Nature. 



