DRINKING HABITS AND WATER LIFE. 23 
IV. 
An interesting note upon the feeding habits of spiders has been com- 
municated to me by the Philadelphia entomologist, Mr. P. P. Calvert. While 
; studying the habits of dragonflies he observed early in May a 
Feeding ; 5 : 
Habits, ‘*Pecies of spider, which appears to be a young Dolomedes sex- 
punctatus, feeding upon newly transformed imagines of these 
insects. ‘The spiders were lurking upon tall grasses and water plants, on 
the margin of a small pool near Bartram’s Garden in Philadelphia, The 
dragonflies had come to these plants to transform, and before their wings 
were dried and ready for flight, while they were yet helpless, the young 
Dolomedes seized them and sucked their juices. The two species which 
were thus preyed upon are Ischnura verticalis Say and Nehalannia posita 
Hagen, both of them small species. Dolomedes, as heretofore 
described (see Index of Vol. II.), is a semiaquatic species, running 
rapidly upon the water to seize insects, and remaining for a con- 
siderable length of time underneath the surface. The mother deposits her 
cocoon in a large leafy nest among the bushes, within which the young 
are hatched. The specimen shown me by Mr. Calvert as taken while in 
feeding on dragonflies was not more than half grown. We thus have a 
glimpse of one of the methods in which this Citigrade species, and doubt- 
less many others, obtain food. It shows also the disadvantages and perils 
of insects during transformation, when they are exhausted by the process 
and have not acquired the natural facilities for escape or defense. 
V. 
Various spiders run fearlessly on the surface of the water; some even 
descend into it spontaneously, the time during which they can respire, 
when immersed, depending upon the quantity of air confined by 
Lae a the surrounding liquid among the hairs with which they are 
clothed. In this manner the European Argyroneta aquatica is 
able to pursue its prey, to construct its dome shaped dwelling, and to live 
habitually in water. There are, however, a few exceptions of extremely 
small spiders, Neriena longipalpis and Savignia frontata, for example, 
which, though they do not enter water voluntarily, can support life in it 
for many days, and that without the external supply of air so needful to 
the existence of Argyroneta under similar circumstances.!_ This is certainly 
a remarkable fact. I have known spiders that seemed to be drowned by 
long immersion in water to revive shortly after being taken out; even those 
plunged in alcohol, if not kept therein too long, will recover from seeming 
death. But that these small and delicate creatures should live several days 
in water surely strains one’s belief in even so trustworthy an observer as 
Blackwall. 
Dolo- 
medes. 
1 Blackwall, Spiders Gt. B. & I., Introduction, page 9. 
