March, 1921] Macro-Fauna of Mirror Lake 173 



material (duckweed, etc.) kept in a battery jar. The pupa was 

 not noticed, and its presence unknown until the emergence. 



Hydrellia ischiaca Loew. This rare species, represented by 

 one adult, bred out under conditions like the preceding. 

 ' Parydra breviceps Loew. This rare species was also repre- 

 sented by one fly bred out as were the preceding. 



Philygria opposita Loew. This kind can be rated as fairly 

 common. While larvae were not seen, pupse were numerous 

 and easily found. They were small, oval, of a brownish color, 

 situated in the parenchyma of Lemna leaves, never more than 

 one to a leaf, and centered quite well in the thickest part. The 

 largest number were obtained September 8, and most of those 

 obtained then bred out as flies September 25. 



Class AR.A.CHNIDA. 



Order Acarina. 

 Water mites were surprisingly rare in Mirror Lake during 

 the period of my collecting. Forms swimming about as con- 

 spicuously as they could hardly be overlooked. Conditions in 

 the pond would have seemed favorable enough for mites. Only 

 two individuals were found, both in the small pond, but unfor- 

 tunately neither specimens nor record of the names have been 

 received from the specialist to whom they were sent for 

 determination. 



Order Araneida. 



Spiders taken in this survey were either on the water's 

 surface, or on vegetation above the surface, or directly on the 

 shore line. At no time did I see a spider dip beneath the sur- 

 face, though one species included here does that. It is realized 

 that the others, though adapted to moist situations, are not 

 properly regarded as members of an aquatic list. 



Dolomedes sexpunctatus Hentz. This can be called a true 

 aquatic spider, for in addition to frequenting moist places and 

 water surfaces, it is known to dive and lurk under floating 

 leaves. It was not common, but specimens were secured from a 

 number of stations. 



Glenognatha (Mysmena) bulbifera (Banks). One young specimen 

 of this non-aquatic species was found on aquatic vegetation. 



Tetragnatha sp. Members of this genus are not aquatic or even 

 moisture loving (Comstock '12j. The few specimens of this genus were 

 found on the water or plants off shore merely by accident. 



