THE PLANKTON OF SHAWNEE CAVE. 387 



pe rat ure of the water approaches this constant slowly, (2) the 

 rate of the air current in this cave is determined by the outside 

 temperature, while the rate of water current is determined by its 

 level, which in turn is determined by rainfall. Since the terres- 

 trial region affects the plankton-inhabited aquatic, both regions 

 need to be considered. 



A careful examination of the bed of the stream was made for 

 sessile and bottom-inhabiting forms with negative results. 1 



Previous Work. Previous studies on the microorganisms of 

 caves have been confined for the most part to the enumeration 

 and description of species. Claus, Schmeil and Joseph have in- 

 vestigated the zooplankton of some of the European caves and 

 have recorded the species. 



In this country records of microorganisms inhabiting cave 

 water have been made by Tellkampf ('45), Packard ('89), Banta 

 ('07) and others. Kofoid ('99) has described a towing net col- 

 lection taken in Echo River, Mammoth Cave, by Eigenmann. 

 This catch contained twenty species. Ulrich ('02) reported 

 twenty-one species from the water of an artesian well at San 

 Marcos, Texas. Among these were two species of cyclops, both 

 of which he regarded as new. 



The Cave. The cave 2 in which these studies were made is at 

 present a rather simple tube with a few side passages. A stream 

 of some size flows through its entire length. The openings of 

 the cave are in Section Four (4), Township Three (3) North, 

 Range One (i) East. These openings are five in number. The 



1 1 am greatly indebted to Dr. C. H. Eigenmann, professor of zoology, for his 

 helpful criticisms and the loan of literature from his private library ; also to Dr. 

 Charles Zeleny, associate professor of zoology, for valuable suggestions. Messrs. 

 F. C. Greene and N. E. Mclndoo assisted in surveying the cave. They are entirely 

 responsible for section II. 



2 The upper end of this cave is not known. It has been explored to a point about 

 two miles above the outlet. At this point a mass of fallen rock nearly closes the 

 passage. Mr. N. E. Mclndoo has crawled through this passage, but it is too small 

 to admit the boat. A stream, which drains a valley some two miles long, flows into 

 an underground passage about four and one half miles southeast of the outlet of 

 Shawnee Cave. This is known locally as "Mosquito Sinks" and is indicated by 

 Newsom (*oi) in section sixteen, township three, range one north. Possibly this is 

 the upper limit of the cave. The openings where the stream " sinks " are too 

 small to be explored. Five hundred wooden blocks, which had been soaked in paraf- 

 fine, were placed in these openings, but none has been taken within the cave, to 

 date. 



