24 AMERICAN SPIDERS AND THEIR SFINNINGWORK. 



Argyroneta has not been found in America, and no spider with habits 



in anywise resembling it, but our spider fauna contains a number of 



species, principally limited to the Citigrades, that are much at home either 



on or within the water. Several species of Dolomcdes habitually 



Rafting jj ye j n ^j ie neighborhood of water, and may be seen continually 



running about upon the surface in search of prey. They avail 



themselves sometimes of floating material in order to rest during 



their predatory excursions. This incidental occurrence, in the case of Dol- 



omedes fimbriatus of England, seems to have been specialized into the 



habit of constructing a rude sort of raft by lashing together floating leaves. 



This raft is utilized as a point of departure for raids upon water insects, 



and as a " lunch room " in which the captured prey are fed upon. It 



floats upon the fens of England, apparently at the sport of the wind. 



Dolomedes sexpunctatus, in the neighborhood of Philadelphia, is able 

 to remain for a long time beneath the surface of water. I have on various 

 occasions timed the period of submergence, and one specimen remained 

 underneath the water forty-two minutes. While thus submerged the 

 spiders are surrounded more or less completely with bubbles of air which 

 have the appearance of a silvery coat of mail, as one looks down into the 

 water. I have alluded elsewhere 1 to the habit of certain Lycosids, as re- 

 ported by Dr. Alan Gentry, to live underneath frozen water during winter, 

 and pass from point to point by means of threads strung upon water 

 plants. This single observation opens up a new and strange chapter in 

 the winter life and amphibious habit of these animals, which invites in- 

 vestigation. No doubt the ability to exist while surrounded with water is 

 of special value during periods of heavy rain, when their burrows 

 Long must be inundated, and when they are themselves submerged for 

 hours or perhaps days together. It is probably true that all 

 spiders can endure a good deal of submerging ; they seem at 

 least to be able to survive under the heaviest and longest continued showers. 

 How easily even Orb weavers can adapt themselves towie water habit may 

 be found by reference to Vol. I., page 160, where it is seen that Tetrag- 

 natha habitually sails over the surface of. Deal Lake, New Jersey, by means 

 of outspun filaments of thread ; and where also (page 161) it is shown 

 that Epeira can avail herself of an accidental float in the shape of her own 

 flossy ball of cocooning silk. 



VI. 



Lycosa tigrina digs a tube in the earth from six to twelve inches in 

 depth, which is bent in a little elbow near the surface. The upper part 

 beyond the bend forms a sort of vestibule, 2 which assumes the shape of 

 a broad, silk lined funnel at the mouth of the burrow. The background 



1 Acad. Nat. Sci., Philadelphia, 1884, page 140. 



2 See Vol. I., Figs. 305, 306, page 323. 



