OF THE EGG URCHIN. 181 



account for the disgust or horror with which we view 

 many of these creatures. Indeed, except in their minute 

 size, they resemble in their characters many of the 

 fabled monsters of antiquity, whose voracity was one of 

 their most appalling qualities. Magnify any of the 

 insect race, or of the worms, to the size of elephants or 

 serpents, and what portentous monsters they become ! 

 Their mouths and jaws seem utterly disproportionate in 

 strength and complexity to the rest of their structure, 

 though not at all disproportionate to the office which 

 these scavengers of creation discharge in the general 

 scheme. But few animals can boast a dental appara- 

 tus equal in complexity to that of the Egg Urchin ; a 

 set of harder-pointed teeth ; more grinding jaws, with 

 a surface regularly " dressed," like that of a mill-stone ; 

 or stronger and more varied muscular bands, by which 

 the motions of the whole structure are regulated. In 

 an Urchin of the usual size this system of bony jaws 

 and teeth forms a conical body, about an inch and a 

 half long, placed with its pointed end toward the large 

 aperture at the base of the shell, and extending back- 

 wards into the body of the animal. It is attached by 

 strong muscles to five bony arches that surround the 

 mouth of the shell, and several other sets of muscles 

 serve to propel it forward, to cause it to retreat, to 

 move the mass from side to side, or to cause the jaws 

 to act on one another, like pairs of millstones. The 

 cone consists of five triangular pieces or jaws, hollowed 

 out, with an opening down the centre in front ; arched 

 behind, and with the two sides flattened and finely 

 grooved. In the hollow of these jaws is placed a long 



