March, 1921] Macro-Fauna of Mirror Lake 151 



Mirror Lake, abundant in fact, and more so than the numbers 

 in the table would indicate. During most of the collecting 

 period it could be found attached to dead leaves and a variety 

 of other objects on the bottom of the small pond. Several 

 females with egg masses attached ventrally, were taken in 

 April and a considerable number of very young ones in May. 



Glossiphonia fusca Castle, another small leech of similar 

 habitat, was rare. Only one individual was taken during the 

 entire survey. 



Placobdella rugosa (Verrill). Only one rather small spec- 

 imen of this "rough leech" was found. Undoubtedly it was 

 rare here. 



Order Gnathobdellida. 



Family Herpobdellidce. 



Herpobdella punctata (Leidy) This large leech was com- 

 mon, but no complete idea of how numerous it was could be 

 formed because of its bottom dwelling habit. Its swimming 

 powers it never seemed to use. It could not have been entirely 

 absent from the bottom of the large pond, even though the 

 collections disclosed none there. Most of those secured would 

 have been missed had it not been for the lowering of the water 

 level in April, which stranded many on the newly exposed 

 mud at station 1. 



Phylum BRYOZOA. 



Collections from Mirror Lake disclosed no specimens of 

 the small but common group of fresh-water Bryozoa, though 

 favorable places for attachment existed in great number, and 

 were examined closely. A specimen of Plumatella polymorpha 

 Kraepalin, on a Physa shell, was observed in an aquarium in 

 the laboratory. The snail was believed to have come with other 

 material from this pond; but this is not sufficient basis for 

 inclusion in the pond list of species. 



Phylum MOLLUSCA. 

 Class Gastropoda. 



Order Pulmonata. 



The small pond was a favorable habitat for snails, princi- 

 pally because of the vegetation there. The large pond on the 

 other hand was very unfavorable not only because of the lack 



