550 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxv. 



it was only a matter of days before they would have passed out of 

 the cave or starved to death. 



13. Etheostoma coeruleum Storer, rainbow darter. Not abundant. 



14. Coitus richardsonii Agassiz, miller's thumb. Abundant. Has 

 been seen a short distance within the lower cave. 



AMPHIBIANS. 



Amphibians were' abundant as individuals, although several spe- 

 cies common in this region were not seen. The water dog {Necturus 

 maculosus), the mud eel (Siren lacertina), and the hellbender 

 (Cryptobranchus alleghaniensis) no doubt live along the river, but 

 no collecting was done there, and none are found on the u farm." 



The economic importance of the amphibians is a subject not often 

 mentioned in the literature of this group. Nearly all frogs and sala- 

 manders are insectivorous during part or all of their existence. 

 Where the individuals live in numbers as great as some species were 

 found here they must exert a beneficial influence, not much less in 

 importance than that of birds, in keeping down insect pests. 



All that is necessary to set off the egg-laying impulse in some 

 species of amphibians is the presence of water at the time the ova 

 are ripe. In the spring of 1907 many eggs of both salamanders and 

 frogs were laid immediately after the heavy rains which fell during 

 the middle of March. At this time sink holes, roadside pools, and 

 other low places were filled with water. The heavy precipitation 

 ceased suddenly and the water evaporated and ran away. Many 

 amphibian eggs which had been laid in these places were left on the 

 ground to dry up without hatching, and many larva 1 perished on 

 account of the pools drying before they had reached adult life. I 

 estimated that not less than one-half of the eggs laid at this time 

 ( and the number of these within a radius of 1 mile must have reached 

 into the hundred thousands) were eliminated because they were 

 deposited where the water supply Avas not permanent. 



AMBYSTOMA JEFFERSONIANUM (Green). 

 JEFFERSON SALAMANDER. 



The adults of this species were not taken, although evidently 

 abundant. On February Lis " eggs were found in a small pond. 

 This little body of water is circular in shape and only about 25 feet 

 in diameter, with a depth of not more than 18 inches. On the 

 above-mentioned date it was free from ice and the water was very 

 clear. The eggs were in small masses, not perfectly regular in out- 

 line nor absolutely uniform in shape, but nearly all had approxi- 



These eggs were in the late segmentation stages and had doubtless been laid 

 some days. The species lias been known to deposit eggs early in January. 



