TRAP -DOOR SPIDERS. 191 



differ from those of its competitors ; for we may be 

 quite certain that it does not exist where we see it 

 by grace and favour, but by merit ; if it is neither 

 stronger, cleverer nor more numerous than its neigh- 

 bours, we may be sure that it has found some means 

 of living which does not interfere fatally with their 

 requirements. Hence the endless diversity of function 

 and habits in all living creatures, which forms such a 

 prolific and marvellous subject for our study and con- 

 templation. 



I am indebted to M. Simon for permission to 

 publish the details given above on C^rtni/.cJienius 

 elongatus, and also for having given me such directions 

 as enabled me to make the sketch from which the 

 drawing at Plate XIII., fig. B, was copied. 



I must however state that this illustration is not 

 taken from an actual specimen, but is prepared solely 

 from his description ; so that it cannot pretend to 

 complete accuracy of detail. M. Simon assured me 

 nevertheless that it conveyed the general appearance 

 of this remarkable nest with sufficient fidelity, and I 

 have been induced to reproduce it here in the hope 

 that it may serve to make my meaning plainer, and to 

 suggest the kind of object which one should look 

 for, if an opportunit}' ofiered. 



Another species of the same genus, Ci/rfauchenius 

 Doleschallii, is known to inhabit Sicily, but the nest is 

 undescribed. M. Lucas has described two species,* 

 belonging to the closely-allied genus Cyrtocejjhalm, 

 both of which appear to construct nests somewhat 

 similar in form to that discovered by M. Simon. 



* Cyrtocepliolus Walclenaeri and terricola, Lucas (H.), Animaux artlcules 

 de. VAlgerie (Paris, 1847-9), vol. i. p. 94-5. 



p 2 



