PULMONART^. 173 



M. Leon Dufour, who has published many excellent me- 

 moirs on the anatomy of Insects, who has especially studied 

 those of Valencia, among which he has detected several new 

 species, and to whose labours the science of Botany is not less 

 indebted, has paid particular attention to the respiratory or- 

 gans of spiders, and it is from him that we have taken our 

 divisions, which consist of those that have four pulmonary 

 sacs — with as many external stigmata, two on each side, and 

 closely approximated — and of such as have but two(l). The 

 first, which embraces the order of the Theraphosse of Walck- 

 enaer, and some other genera of the one he collectively desig- 

 nates by the name of Spiders, acccording to our method form 

 but the single genus 



Mygale. 



Their eyes always situated at the anterior extremity of the thorax, 

 and usually, closely approximated; feet and chelicerse robust; co- 

 pulating organs of the males always salient and frequently very 

 simple. Most of them have but .four fusi, of which the two late- 

 ral or external, situated somewhat above the others, are longest, 

 and consist of three segments, exclusive of the prominence that 

 forms their peduncle. They weave silken tubes in which they 

 reside, and which they conceal either in holes excavated by them 

 for that purpose, or under stones, bark of trees, or between leaves. 

 The Theraphosae of Walckenaer will form a first division, the 

 characters of which are: 1. Four(2) fusi, of which the two that 

 are intermediate and inferior, are usually very short, and the two 

 that are exterior, very salient; the hooks of the chelae doubled un- 

 derneath, or along their carina or inferior edge, and not on the 

 inner side of their internal face, or upon it; eight eyes always, usu- 

 ally grouped on a little eminence, three on each side, forming a 



foi-ming a tail; — 5. Auachne, which does not appear to us to differ from Ange- 

 lena; — 6. Argtopes, Epeirae wliose anterior; lateral eyes are much smaller than 

 the others; — 7- Esro, fifth family of the Theridion, Walck. ; — S. Octale, second 

 family of the Dolomedes, Id. 



(1) Sectionof the Territelae of our first edition. 



(2) 1 have perceived, in the Atypi, vestiges of two other mammillae, those which, 

 in the Spiders of the ensuing division, are placed between the four exterior ones, 

 and are, there, very visible; as they are here but scarcely apparent, I have not 

 thought it requisite to notice them. 



