178 Mr. J. O. Westvvood's Observations 



Such is the correspondence between the feet and the palpi of 

 the females of this genus, but the males form a remarkable ex- 

 ception to the general character of the class, being in fact the 

 only spiders which have six joints in the palpi, in addition to the 

 maxilla, or seven in all, as shown by M. Lucas in his valuable 

 memoir on this genus (in the " Annales de la Societe Entomologique 

 de France," 1837, p. 379). The same author, in his memoir on the 

 genus Hersilia (in Guerin's Mag. de Zool. class 8, pi. 12 and 13), 

 also showed that that genus was anomalous in possessing eight 

 joints in the feet, instead of seven, the usual number, the tarsi 

 being composed of three joints instead of two. He consequently 

 gave to this extra joint of the tarsus the name of Le mesotarse, 

 placing it (as its name indeed implies) between the metatarsus 

 and the tarsus, and in order to establish the correspondence be- 

 tween the joints of the foot of Hersilia, and the joints of the 

 ^a\pus o^ Actinopus $,he proposed the following modifications: — 



PALPI. PIEDS. 



Machoire correspondant a la Hanche. 



Art. sous axillaire (^Sav.) A rexinguinal (^Sav.) 



Humeral (Sar.) Au femoral (5au.) 



Cubital (Sav,^ Au genual (Sau.) 



Radial (Sav.) Au tibial (Sau.) 



Metadigital (^Lucas) Ait, mesotarse (Lucas.) 



Digital (Sav.) Au tarse (Sav.) 



I cannot, however, exactly agree with M. Lucas that it is " facile 

 de voir que les articles qui composent les organes de la mandu- 

 cation correspondent entierement a ceux de la locomotion," there 

 being eight joints in the feet of Hersilia, and only seven in the 

 palpi of Actinopus $ . M. Lucas has indeed added " le meta- 

 digital correspond au mesotarse et enfin le digital sur le dernier 

 article (of the palpi) est le correspondant du tarse, qui se compose 

 ordinairement de deux articles, le metatarse et le tarse;" thus 

 increasing the difficulty by placing his new joint, the mesotarse, 

 or middle joint of the tarse, before the basal joint, or the meta- 

 tarsus. 



By taking a more generalised view of the matter I have no 

 doubt but that we shall arrive at a very different conclusion from 

 that obtained either by Savigny or M. Lucas. The structure of 

 the female palpus, as above stated, evidently corresponds with 

 that of the feet, the two terminal joints of the feet being soldered 

 together in the palpi of the female. This supposition receives 

 full corroboration, by the fact that the male palpi have the two 

 terminal joints distinct, as stated by M. Lucas. 



