100 



turbs its clearness or destroys its piu-ity ; and owing to its mass 

 its temperature changes slowly and the range is moderate. 

 There are also deep passages, once portions of the river-bed, 

 now almost land locked, but still sufficiently open to the river 

 to admit fresh water and maintain a constant level. Aquatic 

 life in these channels is phenomenally luxuriant for a North 

 American station in latitude 43"". Again there are small 

 rivers of creeks entering the m^ain river, the estuaries of 

 which are deep, c|uiet, and supplied from above with swamp 

 and land drainage, whilst their constancy is assured by that of 

 the Niagara. These are teeming with a vast variety of micro- 

 scopic plants and animals from early summer to December. 

 These conditions are especially favorable to the growth of 

 sponges and here they are found in remarkable abundance. 

 Whilst the number of species recorded compares favorably with 

 any explored locality in the world, the abundance of representa- 

 tives is, according to my experience and the testimony of others, 

 quite unsurpassed. 



The specimens of this collection were obtained by Mr. 

 Mills, by personal exploration of our own vicinity, and also in 

 Iowa, Wisconsin, Florida and Ohio, and by exchange from other 

 localities. They were preserved by drying. Every example has 

 been re-examined to confirm determinations already made or 

 to determine such as were not labeled. In most cases the fol- 

 lowing method proved rapid and satisfactory. A row of watch 

 glasses, each with a few drops of carbolic acid, were placed on 

 the work-table and a selected fragment of a sponge placed in 

 each with proper numbering to prevent confusion. After a 

 short interval examination could be commenced. This was 

 done by t»ansferring material to ordinary slides and examining 

 in the acid. The statoblasts were soon sufficiently transparent 

 to permit a determination of the structure by a one-fourth inch 

 objective. 



The following genera are represented: Spo/igi/Ia, Mcyciiia, 

 Hctcroiiicycnia, Tubclla and Caitcriiis. All are represented by 

 one or more species in Western New York. A brief key to 

 the genera is here introduced to aid any intending students of 

 local forms. 



