SOME AQUATIC WORMS, ETC. 20I 



Key to Genera of Microscopic, chiefly Fresh-water, Worms. 

 (Oligochcetd) . 



1. Body with both bristles and podal spines {a). 



2. Body with podal spines only (p). 



3. Body with bristles only (/). 



a. Anterior extremity without a finger-like prolon- 

 gation (d). 



a. Anterior extremity with a flexible, finger-like 



prolongation. Pristma, i. . 



b. I'odal spines forked; worms aquatic (c). 



b. Podal spines not forked; worms aquatic {g). 



b. Podal spines not forked ; worms living beneath 



decaying bark of dead trees. Enchytrceus. 2. 



c. Podal spines, from six to ten in each cluster, the 



clusters in two rows. ChcBtogdster, 3. 



c. Podal spines, two only in each cluster, the clus- 



ters in four rows. Lumbruulus , 4. 



d. Posterior extremity without finger-like append- 



ages (^). 

 d. Posterior extremity widened, ciliated, with sev- 

 eral retractile,^ finger-like appendages. Dero, 5. 



d. Posterior extremity ciliated, with two long, non- 



retractile, finger-like appendages. Auldpho- 

 rus, 6. 



e. Biristles and' podal spines in separate rows {h). 



e. Bristles and podal spines alternate in the same 



row. Str^phuris, 7. 

 /. Body variegated with brick-red or orange colored 



sp,ots; blood colorless. yEolosdma, 8. 

 g. Podal spines in clusters of four each; body the 



color of raw meat. Ocnerddrilus, 9. 

 g. Podal spines in clusters of two each. Lumbricu- 



lus, 4. 



