368 



THAT'S IT ; 



and to fill them with air brought from the 

 surface. In constructing its nest, the spider 

 rises to the surface, and, with its head down- 

 wards, places the point of its abdomen in 

 contact with the external air. Expanding the 

 filaments at that point, it encloses, in again 

 sinking, a small bubble of air, which it retains 

 in a rounded form, independent of the bubble 

 which covers the rest of the abdomen. It then 

 swims towards the edge of the plant to which 

 the nest is to be attached, and touches the 

 little bubble in such a manner as to make it 

 leave its own body, and adhere to the edge of 

 the plant. The spider again mounts, and 

 brings down another bubble, and so on in succes- 

 sion, until he has a number of bubbles collec- 

 ted, furnishing a sufficient supply of air, around 

 which he begins to spin a web, by means of 

 which he brings the separate bubbles together, 

 so as to form a single one large enough to con- 

 tain his body. Living afterwards in this little 

 balloon, the spider spreads filaments round the 

 aperture, by which means many small water 

 insects are caught and detained ; and these 

 compose its food. Sometimes insects are caught 

 in the water, brought to the surface, and de- 

 voured dry, or else taken and consumed in 

 mid-water ; sometimes those caught in mid- 

 water are carried to the nest ; sometimes they 

 are hung up as stores for future consumption.* 



Among the curious tenants of 

 the water, is a sluggish and 

 somewhat unat- 

 tractive creature, 

 the water scor- 

 pion, 13, so called 

 from the resem- 

 blance of its an- 

 terior members 

 to those of the 

 scorpion. They 

 use their fore- 

 legs to seize other 

 aquatic insects, 

 and convey them 

 to their mouth?. 

 The most common kind is about 

 two- thirds of an inch long, of an 

 ashy colour, with the upper sur- 

 face of the abdomen red. 



The large water beetle, dyticus 

 marginalise 14, is one of the most 

 formidable carnivorous insects of 

 the pond. They are exceedingly 

 voracious, especially in the larva 

 state, 15, seizing and devouring 



Sowerby's Popular History of the Aquarium. 



1201. 



insects of large size, and even 

 small fishes, destroying them by 

 exhausting their juices, and then 

 abandoning the solid parts. They 

 even destroy gold fish, by nibbling 



1202. 



at their fins, and sucking them. 

 If placed in cups or glasses, and 

 fed with bits of raw meat, they 

 will so completely abstract the 

 juices of the meat, that it will 

 look completely white. 



They ascend frequently to the surface for the 

 purpose of breathing, and it appears as if they 

 sometimes do this through their tails ; for they 

 lie immersed all but the hinder extremity, 

 which protrudes from the surface. Here they 

 appear at rest, balancing on their oar-legs, 

 which they stretch at right angles. Although 

 pretty constant denizens of the pool, they 

 cannot subsist without occasional access to the 

 air; and sometimes creeping up the rushes 

 to take flight they mount up into the air 

 perpendicularly, like a lark. The descent is 

 equally direct, resembling rather a fall than a 

 flight. It is surmised that they are guided in 

 their descent by the reflection of light from the 

 water's surface ; for they have sometimes been 

 deceived and have fallen with violence upon 

 glazed garden frames, which had apparently 

 been mistaken for water. During the winter 

 their habits are by no means uniform. Some 

 bury themselves, and remain for the season in 

 a state of torpidity ; others retain their natural 

 briskness, and will remain in the water when 

 frozen over, swimming under the surface, and 

 coming to any opening to take air.* 



The larva of this beetle is so 

 voracious, that if two of them be 

 placed in a cup of water, without 

 other food, in about an hour one 

 of them will conquer and devour 

 the mother. 



* Sowerby'o Popular History of the Aqnatiusa 



