34 



cies could have been introduced from the time it was first 

 collected up to the time of its examination by me. This is con- 

 firmed by the fact, that several of the species are entirely differ- 

 ent from any occurring in the eastern portions of the United 

 States, 



Having thus unexpectedly an opportunity to study the recent 

 animalcules of so interesting a locality, I examined them care- 

 fully ; and I now offer the following results of my observations as 

 a slight contribution to the knowledge of the geographical dis- 

 tribution of Infusoria : 



1st. The water of the Mississippi, at St. Louis, abounds in 

 soft, as well as siliceous-shelled Infusoria. 



2d. The species observed by me, as far as I could identify 

 them with species described by Ehrenberg, were the following, 

 namely : 



Micrasterias boryana, 

 " elliptica, 



" tricycla, 



Navicula amphirhyncus, 

 " sigma. 



Oxytricha ? 



Rotifera vulgaris, 



Stylonichia ? 



Arthrodesmus acutus, 



" quadricaudatus, 



Chcetonotus larus, 

 Coleps hirtus, 

 Euglena triquetra ? 

 Eunotia westermanni, 

 Fragillaria constricta, 



" rhabdosoma, 



Furcularia gibba, Surirella campylodiscus, 



Gallionella distans, Synedra ulna. 



3d. All these were observed by me in a living state, and most 

 of them were in g.rcat abundance, and from their activity as well 

 as other characters they appeared to have suffered no injury 

 from transportation. 



4th. The remarkable Surirella campylodiscus which abounds 

 in the water from St. Louis, has not before been found in the 

 United States, but is mentioned by Ehrenberg (Verbreitung, &c., 

 p. 100,) as a Mexican species. 



5th. No traces of any Phytolitharia were seen ; neither was 

 the cosmopolite species Pinnularia viridis detected. 



6th. The inhabitants of St. Louis consider the water which 

 they drink as remarkably wholesome, and are surprised that 

 strangers wish to have it filtered for their use. Whatever its 

 effect on health may be, it is certain that it contains a suflicient 

 amount of animal matter to be somewhat nutritious. 



