MICROSCOPICAL OBSERVATIONS. 13 



HOPETON. continued. 



In a ditch leading from a small artesian well in the rice fields at Hopeton, 

 the following forms were noticed, viz : 



Closterium lunula, Ehr. Syiiccha vitrea, Kg. 



lanceolatum, Kg. Arcelki dentata, Ehr. 



Eunotia gibba, Ehr. Euglena viridis, Ehr. 



Surirella splendida, Ehr. Rotifer vulgaris, Sclir. 



Iii a ditch behind the Negro Hospital at Hopeton, I found "the following, viz : 



Closterium Dianas, Ehr. Dinobryon vulgaris, Ehr. 



moniliferum, Ehr. Peridinium cinctum, Ehr. 



Docidium clavatum, Kg. Rotifer vulgaris, Sclir. 



Himantidium arcus, Ehr. and several species of Cyclops, Daphniaand Gam- 



Synedra vitrea, Kg. marus. 



GLYNN CO., GA. continued. 



ST. SIMON'S ISLAND. 



Iii the salt marsh mud from the " Cut-off" at the north end of St. Simon's 

 Island, the following species were found, either alive or evidently in a very re- 

 cent condition, viz : 



*Campylodiscus argus, B. GallioneUa sulcata, Ehr. 



Coscinodiscus oculis iridis, Ehr. Rhaphoneis rhombus, Ehr. 



radiatus, Ehr. Terpsinoe musica, Ehr. 



subtilis, Ehr. Triceratium favus, Ehr. 



*Eupodiscus radiatus.B. Zygoceros rhombus, Ehr. 



The same forms were noticed in mud from the " Inland Passage" from Darien 

 to Jacksonville, Fa. The resemblance of these marsh muds to those thrown 

 out in digging the canals of the rice fields, and the identity of the forms contained 

 in them, serve to show that the rice fields were once salt marshes, and have been 

 cut off from the influence of the ocean either by elevations of the coast, or 

 changes in the course of the rivers. It should be borne in mind, however, that 

 marine forms occur in estuaries far above where the surface water is brackish. 



