entom6straca and phyll6poda. 267 



and conspicuous. The eggs are placed in a brood 

 cavity, as shown in the figure, and there hatched, the 

 young being very different in appearance from the 

 parent. Daphnia is common in the spring. 



2. Scaphol£beris. 



The shell is somewhat beaked and usually dark 

 brown. The surface may be indistinctly reticulated 

 or entirely smooth. From Bdsmina, for which the be- 

 ginner may be inclined to mistake it, the absence of 

 the curved, cylindrical antennae common to that 

 species will distinguish it. The posterior spines are 

 short. The eye is large and conspicuous. The egg is 

 carried in the brood-cavity, and it is said that but one 

 &gg is present at a time. This Entomostracan is com- 

 mon. 



3. B(5sMiNA (Fig. 179). 



The -student will have no trouble in recognizing 

 Bdsmina, on account of the long, large, cylindrical an- 

 tennae, each one curving downward from the side of 

 the head like the trunk of a microscopic elephant. 

 The shell is oval, colorless, and 

 the posterior border bears a 

 spine at its lower angle, never 

 at any other point. The net- 

 work of lines on the surface may ' 

 extend over the entire shell or 

 be restricted to some one part. 

 Fig. 179.— Bfismina. The eye is large. The eggs are 



hatched in a brood-cavity on the 

 back beneath the shell. The heart is visible near the 

 center of the back. Bosmina is not so common as 

 Daphnia. 



