INTRODUCTION. 



of numerous floating lines, and depends upon atmospheric con- 

 ditions, being most common in early autumn, and only in very 

 fine, settled weather. Both in autumn and spring (particu- 

 larly the latter) there appears to be a great restlessness and 

 moving about of immature spiders of many kinds, quite 

 as difficult to be fully accounted for as the migrations of 

 birds. On a bright, and tolerably still, spring morning, 

 railings, especially those fencing a causeway across water- 

 meadows and swamps (situations peculiarly prolific in spiders), 

 and the parapets of bridges, are often thronged with individuals 

 of numerous species, principally of Lycosides and Theridiides ; 

 these may be observed running up and down on the upper railing, 

 elevating themselves on tiptoe, thrusting up the abdomen, and, 

 with a small muscular effort, jerking themselves off, and float- 

 ing away in the breeze on their silken lines, which may often be 

 seen issuing from the spinners ; the lines, in the first instance no 

 doubt, are propelled from the spinner at the will of the spider, but 

 are afterwards further drawn out by the influence of the current of 

 air, and when sufficient line has been drawn out to float the 

 aeronaut he gives a little jump and sets sail. 



Spiders may sometimes be found adhering to the white flakes 

 of web, or flocculi mentioned above, but this is not by any means 

 usually the case. 



From the few remarks here made on this part of the subject, 

 it will be seen that the popular idea that gossamer is due to a 

 particular species of spider called the " gossamer spider" is quite 

 erroneous. 



Some other uses of Silken Lines. 

 A very convenient use of the silk lines is made by one of our 

 commonest "jumping spiders," Epiblemum tcenicum, Clerck. 

 This spider is found on perpendicular walls, and always has a 

 line trailing behind it from the spinners, and adhering to the 

 surface of the wall. The spider in this situation is thus enabled 

 to leap from a considerable distance upon its prey, which it could 

 not possibly do unless it had a line to bring it back again to the 

 perpendicular surface it had left at its spring. Another use 



