on the Species of Trap-door Spiders. 181 



son couvercle les Spines et les crochets cornes dont sont munies 

 ses ma^hoires." The extremely powerful and rugose structure of 

 the third pair of feet immediately suggests the idea, that whilst 

 the preceding feet are employed in holding down the valve, this 

 pair of feet is used in holding the spider at the upper part of its 

 nest, their strong muscles, by being forced downwards, prevent- 

 ing the spider from being drawn upwards ; and hence it is of much 

 greater importance that this pair of feet should be strong rather 

 than the hind pair. Sometimes after disturbing the spider I 

 found that it spun itself in its nest by fastening the loose side of 

 the valve to the lining of the cell. After some time I found a 

 number of young in one of the nests ; these were of a very pale 

 colour, their motions were very slow, and they were constantly 

 observed upon the inner lining of the nest, and never on the back 

 of the spider. 



P.S. (July, 1842.) The Baron Walckenaer, in his supplement 

 to the second volume of his " Histoire Naturelle des Insectes 

 Apteres" (p. 440), after noticing the identification established 

 by me in the preceding article (an abstract of which appeared in 

 the " Annals of Natural History" shortly after it was read before 

 the Entomological Society) between Mygnle nidulans and the 

 genus Actinopus (or Sphodrus, Walck.), and the probable identity 

 which I suggested might exist between the M. nididans and the 

 Sphodros A bbotii, both being natives of new world, adds, however, 

 " mais nous sommes surpris de trouver une Theraphose de ce 

 genre en Barbaric. N'y ait-il pas erreur dans la provenance 

 pour cette derniere espece ? ou est-il bien vrai qu'elle apparti- 

 enne au genre Sphodros ?" 



The description given in the preceding memoir of my new spe- 

 cies will, I think, sufficiently answer the latter of these questions 

 in the affirmative. The former will, perhaps, be best answered 

 by transcribing the original letter forwarded to this Society with 

 the living insects themselves. 



" 7th October, 1839. 

 " Sir, 



" Mr. Drummond Hay, H. M.'s Agent and Consul-general at 

 Tangiers, has requested me lo present the Entomological Society 

 with two specimens of the mason spider, with their nests. 1 have 

 every reason to believe that these insects are alive, but of course 



