in the fre^^ll \\n\vv basins ol liis own Slate, Mimiesota. t" 

 '.vliicli he has chieMy (••'ntined his atter.lioii, principally in 

 the i:i<>u|)s of Cladocera and ('(>pe{)<)(la. He has surveyed 

 the .distrihution of species in tiie liiiled Stales and lias 

 prepared generic tables for determinalive study. 



The " ^iicro^^•aphi(• Dictionary'Ms indispensable, and its 

 descriptions, references, and plates replace to some extent 

 the possession of the other specialtretitises. 



In tlie sprinL"- of this year (18^4) the writers were reciuesled 

 by Mr. W. A. ConcUlin. Sui)erintendent of the Central Park 

 Zoological Gardens, to make an exuniination of the micro 

 scopic and other life contained in the lakes of Central Park. 

 N. V.The re(|uestw\as accompanied by a peimit to dredtre the 

 lakes and enjoy the irse of the park boat. The examination 

 made has been to some extent experimental and provisional. 

 Neither of us felt fully justified in undertakin/L? the labor, 

 as want of time, and more seriously want of experience, 

 would interfere with its thorouirhness, and the variety of 

 topics embraced in the research was thought of with appre- 

 hension. The temptation proved, however, stronger than, 

 as the result may show, oi r prudence, and the task was nn- 

 dertakeii. Imperfect as it is, and possibly not in every in- 

 stance satisfactorily authenticated, the list .so far as we know- 

 is the first of its kind in connection with the Central Park, 

 and can be at least regarded as a contribution to the natural 

 history of New York Island. At any rate, howevei incn«ii- 

 plete the list may appear, the catalogue of papers appended 

 to it will prove valuable, and may help to justify the papers 

 publication. 



The two lakes whose waters were examined during tliis 

 past summer are situated at opposite extremities of the i)ark, 

 the larger eml»racing an area of 20 acres, between 74th an(i 

 77th Street; the smaller, at the northern end of the park, on 

 5th Avenue, representing a square surface of about 12 acres. 

 The greatest depth in either does not exceed 1:} ft. The 

 water supply of these ponds is (U^rived from the Croton ant! 

 from the surface drainage of the nei<4liboring slopes; Hie 

 roadways, drives, and foot-paths wliicli arrest a great part 

 of the rainfall in the vicinity of the lakes are drained into 

 underground pipes, which again empty in the lake. The 

 lakes are stagnant ponds, and the water is foul and impot 

 able. The larger and more southern lake is tenanted with 

 aquatic fowl belonging to the |)ark gardens, and they must 

 to some extent arrest the multiplication of crustaceous, 

 molluscous, and tish life. The various inlets, sinuosities, anil 

 bays along the shores were found to be good hunting places, 

 and we adopted the use of a surface net, which iirouglit us 

 many species not discovered along the margins of the jiond. 

 This net was a shallow i^ieve of coarse linen attached to an 

 iron hoop; the whole suspended from the stern of the 



