THE ()STk.\(()|)A 



Notodromas appears purely as a suninuT form. It winlcre in 

 different ''egg stages," develops in Ai)ril or May. ami I n. 



ber has entirely disappeared. Cypridopsis vidua and ■ .„- 



coiigruens appear in early spring and last until late autumn I .,■ 

 spring forms appear to have a much shorter lil\- history. 



These forms may be collected in great variety and' abundance 

 by drawing a Birgc or cone net ihrou.^h submerged plants prt-st-nt 

 in ponds, slow streams, and lakes, and by stirring uj) the lx)ttom 



ooze and slime, and drawing the weighted net to and fr • ■- '^ - 



bottom. 



In this manner not only the free-swininiing forms may be cap- 

 tured, such as Cypris, Cypridopsis, etc., but typically })ottom forms 

 such as Candona, Herpetocypris, etc., may also be include<l. By 

 emptying the mud and all other accumulations in a beaker of 

 water, and stirring well, it will usually result in many of the Ostra- 

 coda getting air caught between their vaives, thus causing them to 

 float on the surface, from which they may be readily removed 

 with a "medicine dropper" or pipette. The use of a small hand 

 lens is advisable in determining whether or not Ostracoda arc 

 surely present. In any case, the ''catch" may now be concen- 

 trated by carefully pouring oil the contents of the beaker from 

 the sediment in the bottom into a small dip net made of Swiss or 

 bolting cloth. 



After washing out as much of the soluble or other matter as is 

 possible, the remainder may be emptied into a Syracuse watch 

 glass or other shallow vessel containing but a small (|uantity of 

 water. Thus the catch is condensed to such bulk as may now be 

 easily transferred to small vials of preser\ati\-e tluid such as 90 

 per cent alcohol, or a mixture of 80 per cent alcohol and glycerin 

 in about the proportion of 10 to i. However, killing had k-tler 

 be done in about 70 per cent alcohol, which should \yc gradually 

 increased in strength, as in this manner the shells are more 

 likely to remain open than when killed in alcohMl ..f :, hi-h.-r 



percentage. 



If a large quantity of living forms should be desired, the entire 

 catch of a locaHty may be poured into a si)ecial pint strainer jar 

 (Fig. 1248). 



