MICROSCOPICAL OBSERVATIONS. 



27 



NORTHERN LOCALITY, NEAR PROVIDENCE, R. I. 



For the sake of comparison with the above lists of Southern forms, I give here 

 the names of the species noticed by me in Wainskut Pond, near Providence, 

 R. I., on the 18th of July. 1850. 



DESMIDIE.-E. 



Ankistrodesraus falcatus, Corda. 

 Arthrodesmus convergens, Ehr. 

 Cosmarium ovalr, Ralfs. 



undulatum, Corda. 

 Closterium Diana?, Ehr. 



angustatum, Kg. 

 lineatum, Ehr. 

 Jenneri, Ralfs. 

 " moniliferum, Ehr. 



Docidium nodulosum, Breb. 

 Desmidium Swartzii, Ag. 



quadrangulatum, Ralfs. 

 Didymoprium Borreri, Ralfs. 

 Euastrum ansatum, Ehr. 

 " circulare, Mass. 



didelta, Ralfs. 

 " elegans. Breb. 



O * 



" gemmatum, Kg. 



" oblongum, Ralfs. 



rostratum, Ralfs. 

 verrucosum, Ehr. 

 Hyalotheca dissiliens, Breb. 

 Micrasterias pinnatifida, Kg. 

 " truncate, Breb. 



denticulata, Breb. 

 rotate, Ralfs. 

 Penium digitus, Breb. 



" margaritaceum, Breb. 

 Pediastrum pertusum, Kg. 



" boryanum, Menegh. 



ellipticum, Hass. 

 " heptectis, Menegh. 



tetras, Ralfs. 

 " selenaea, Kg. 



* Scenedesmus obliquus, Kg. 



obtusus, Meyen. 



quadricauda, Breb. 

 Sphajrozosma excavatum, Ralfs. 

 Staurastrum alternans, Breb. 



gracile, Ralfs. 



hirsutum, Ehr. 



Spirotaenia condensata, Breb. 

 Tetmemorus Brebissonii, Ralfs. 

 Xanthidium fascieulatum, Ehr. 



DlATOMACE.K. 



*Diatoraa stellaris, B. 

 Eunotia serra, Ehr. 

 Himantidium arcus, Ehr. 

 Gomphonema acuminata, Ehr. 

 Tabellaria flocculosa, Ehr. 

 " fenestrate, Ehr. 



INFUSORIA. 

 Arcella vulgaris, Ehr. 

 Brachionus Bakeri, Ehr. 

 Coleps hirtus, Ehr. 

 Difflugia proteiformis, Ehr. 



" spiralis, B. 

 Dinobryon sertularia, Ehr. 

 Euglena viridis, Ehr. 



" pleuronectes, Ehr. 

 Floscularia ornate, Ehr. 

 Melicerta ringens, Schr. 

 Peridiniuin cinctum, Ehr. 

 Rotifer macrourus, Ehr. 



" vulgaris, Ehr. 

 Stentor polymorphus, Ehr. 



See also in the Appendix a list of forms found near Salem, Mass., by Thomas 

 Cole, Esq. 



By consulting the above lists, the species found at each locality will be seen. 

 The following tables will show the same in a more condensed form, and will 

 also exhibit the geographical distribution of species. 



