660 



THE AMERICAN NATURALIST [Vol. XLII 



the animals revived when water was added it was as- 

 sumed that the method of drying of the lot was imper- 

 fect but if, on the other hand, those animals that were 

 known to be able to withstand drying revived, when water 

 was added, the method of drying of the lot was deemed 

 satisfactory. It may be possible, however, that the indi- 

 viduals of different species, since they vary greatly in 

 size and form, require different methods for being suc- 

 cessfully dried and again revived. But if revival after 

 desiccation is of general occurrence for adult rotifers the 

 various methods of drying used in the experiments ought 

 to have given a fair percentage of positive results. 



The individuals of some of the species were obtained 

 in countless thousands, either in nature or in artificial 

 cultures, others were less numerous and only a few thou- 

 sand or a few hundred individuals were obtained. In a 

 small number of species only a few individuals were 

 found and used in the experiments. 



Jennings 1 classifies the rotifers in five orders: (1) 

 Bdelloida with two families; (2) Seisonacea with one 

 family; (3) Rhizota with three families; (4) Ploima with 

 eighteen families; and (5) Scirtopoda with one family. 



In the experiments performed no individuals were 

 used belonging to the order Seisonacea which contains 

 all marine forms, nor were there used any individuals of 

 the order Rhizota which contains all the fixed forms, 

 Representatives were used from one family of the order 

 Bdelloida, from fifteen families of the order Ploima, and 

 from the one family of the order Scirtopoda. Thus the 

 forty-five species used represented seventeen of the 

 twenty-one families in the three orders just mentioned. 



The following species were used in the experiments : 

 Order 1. Bdelloida. 



Family 1. Philodinadae. 



Species. Rotifer vulgaris? R. macrurus? Philodina roseola,' 

 P. carina.* 

 Order 4. Ploima. 



Suborder 1. Hloricata. 



1 Amer. Nat., Vol. XXXV. p. 725. 



