Species of Bidlerjli/ from 3Iexico. 43 



body, " sont constamment tetrapodes." The insect in question af- 

 fords a striking contradiction to this rule*. 



The form of the j)upa excludes it from the two typical families 

 Nymphalidce and PapilionidcB, as characterized by Mr. Swainson in 

 the Philosophical Magazine for March 1827 ; whilst the mode of sus- 

 pension and structure of the legs conjointly remove it from his three 

 aberrant famihes Hesperiidce, Polyommatidcs and Heliconiidce. From 

 the Hesperiida, NymphalidcB and Lyccenidce, as characterized by Mr. 

 Stephens t, the structure of the fore legs and antennae remove it; 

 but it would fall into his remaining family Papilionidce, except that 

 the pupa is not girted across the body. 



On referring, however, to the valuable remarks contained in the 

 most scientific work hitherto published upon the Lepidoptera, I mean 

 Dr. Horsfield's ' Lepidoptera Javanica,' we gain a clue to its real situa- 

 tion, which, however, appears to me to disturb the series of transitions 

 proposed in that work. This situation I consider to be osculant be- 

 tween the stirps typified by Papilio {Chilognathoniorphu, Horsf., also 

 containing the genera Pieris, Pontia, &c.) and the Thysanuriform 

 stirps of Dr. Horsfieid, containing Hipparchia, &c. 



In some respects this genus might be regarded as osculant be- 

 tween the Chilognathiform and Chilopodiform stirpes of Dr. Horsfieid, 

 but this author has satisfactorily shown that this situation is occu- 

 pied by the genera Evplwa, Idea, Acrcea, and Heliconia. 



On the other hand, in the mode of suspension, the nearly smooth 

 chrysalis, and the tarsal appendages, it seems to ajjproach the Hippar- 

 childce, whilst the obtuse head of the chrysalis, perfect anterior legs, 

 and the form of the palpi, as well as the tarsal apparatus, show an 

 equal affinity with such of the Papilionidce as approximate towards 

 Pieris, Pontia, &c. 



From these observations, the necessity will be at once perceived 

 of establishing a distinct genus for the reception of this insect, and 

 which may be named, from the perfect structure of the fore tarsi, 



* It is a circumstance of mucli singularity, and one wliich appears not easily 

 reconcileable with our ideas of the instincts of animals, that those butterflies which in 

 the perfect state are furnished with six perfect legs, attach themselves, on assuming 

 the pupa state, in such a position that on arriving at tlie perfect state they will have 

 occasion only to burst their fetters and creep at once along the surface upon which 

 they have been affixed ; whilst those butterflies which have the fore legs rudimental, 

 and apparently incapable of rendering any assistance, suspend themselves by the 

 tail in sucli a position that they must necessarily come into the perfect state head 

 downwards, and have to ascend the outside of the fragile pupa-case, with the assist- 

 ance of their four hind legs, before they can obtain a sure footing on the twig ov 

 leaf from which they have been suspended. 



f Illust. Brit. Ent., HausielL, vol. i. p. 5. . 



