ENEMIES AND THEIR INFLUENCE. 411 



characteristic of the species and not an accidental formation, will show that 



it makes an admirable protection against heavy rains, which sink away into 



the first burrow as a kind of reservoir, enabling the spider to escape 



2. Lepto- lyy Q^Q diverging branch. Against enemies who jjursue it into its 

 pe ma s ^^^^^ ^j^^^ structure also presents an effectual defense, for, while an 

 Burrow enemy naturally would rush downward into the first direct pass- 

 age, the spider may escape by the lateral branch. Supposing that 



the enemy, observing the mistake, ascends and follows along the branches, 

 the spider has the opportunity to push up into the second branch while the 

 pursuer, again following its natural instinct, would rush down the second 

 perpendicular tube. I am here in the region of conjecture, but perhaps no 

 better explanation presents itself. 



A third stage in the development of this defensive industry is repre- 

 sented at Fig. 344, which shows the external tube of Leptopelma elongata.^ 

 This is simply a lily shaped tube of jmre white spinningwork, 



3. Silken j-jj^jug directly above tlie burrow, and supported by surrounding 

 ™ foliage. The purpose of this structure has not been positively 



determined. As able a naturalist as A. R. Wallace has conjectured 

 that it may be deceptive in its uses, its resemblance to a flower attracting 

 to it insects, which are thus preyed upon by the proprietor. Such elevated 

 objects are certainly apt to attract insects, who are disposed to alight upon 

 them even without regard to their promise of providing food. But I am 

 inclined to believe that Leptopelma's silken lily serves as a watch tower 

 from which she can observe the approach of enemies and make good her 

 escape in time. Moreover, I believe that it is possible for her to pull 

 together the sides of the sheeted turret and thus erect a barrier between 

 herself and some of her feebler pursuers. 



Another form of defensive industry is presented at Fig. 345, which is 

 the exterior part of the turret tube of Dolichoscaptus inops Simon. This 



is about an inch in height, and is composed of mingled chippage 



4. Con- .,j^,| i^^^ifi^ a sort of debris of chopped straw and soil. 



z, A still further stage is shown at Fig. 346, which represents a 



Doorle'ss. columnar turret of Dolichoscaptus latastei several inches high. 

 This resembles the tower of the preceding species, but adds thereto 

 a hinged covering after the manner of the trapdoor. This turret is also 

 composed of chippage and debris of various sorts gathered from the neigh- 

 borhood, and is supj^orted upon the surrounding foliage, which in 



5. Trap- ^j-^g drawing is a plant of Lavandula dentata. All the uses to 

 rp which such an elevated structure can be put are served by this 



ingenious structure, and, in addition, the trapdoor is manifestly 

 intended to defend the inmate from the assault of enemies. 



We come now to the trapdoor nests of Nemesia meredionalis, and other 



' Cyrtaurhenius elongatus; see Volume I., page 322, Fig. 304. 



