176 DROPS OF WATER. 



The genus BracJiionus has a lorica like a tortoise- 

 shell, and both front and base are spined; in 

 some species it is smooth, in others rough. The 

 rotatory organs are double, and the tail or foot is 

 forked; the eggs are attached, and sometimes 

 as many as ten are thus carried about. It has 

 a single eye. B. poly acanthus (Drop IV. fig. 14) 

 is one of the most common. It has a smooth 

 lorica, with two very long spines and three 

 short ones at the base, the upper part having 

 many ; the wheels do not extend much beyond 

 the edge of the lorica : the tail is strong, and 

 powerfully grasps any substance in the water. 

 B. militaris has the lorica rough, four spines at 

 the base, and twelve long ones at the upper end. 

 B. urceolaris is often seen in vast numbers in 



