STILODES.— LEPTINOTAESA. 227 



base, forbid, however, to include the species in the latter genus. The palpi in different 

 species of the same genus show occasionally a good deal of variation in these insects ; 

 and it is difficult to fix a limit, unless accompanied by other characters of a more 

 constant kind ; I have therefore thought it best to leave the present species in Stilodes. 

 I must add, further, that the tibiae in the insect before me agree with those of the 

 genus Leptinotarsa, from which the totally different palpi distinguish it ; so that it 

 seems to be an intermediate form of several closely allied genera. The specimen in 

 my collection is of a darker colour (light brown above) than the other, but agrees in 

 all other respects. 



LEPTINOTAESA. 



Leptinotarsa, Stal, Of v. af K. Vet. Ak. Forh. 1858, p. 475. 

 Myocoryna, Stal, ibid. p. 316. 

 Chrysomela, Stal, Monogr. Chrys. Amer. p. 154. 

 Doryphora, Rogers, Proc. Ac. Phil. viii. 1856, p. 30. 



Leptinotarsa, although resembling in general appearance the preceding genus, was 

 founded by Stal on the different comparative length of the palpi, in which the terminal 

 joint is much shorter than the preceding one and truncate, and on the structure of the 

 tibise, which show a more or less distinct groove, extending sometimes to half their 

 length. This latter character, however, is in some cases almost obliterated, and nothing 

 but the shape of the palpi, taken conjointly with the other characters, remains to 

 identify the genus. The species seem entirely confined to North and Central America. 



1. Leptinotarsa cacica. (Tab. XIV. fig. 23.) 



Leptinotarsa cacica, Stal, Diagn. 1858, p. 475; Monogr. Chrys. Amer. p. 156 x ; Dej. Cat. 3rd ed. 

 p.421 2 . 



Hab. Mexico 1 2 , Toxpam, Cordova, Orizaba (Salle), Misantla, Cerro de Plumas 

 (Edge). 



There is a good deal of difference in size in this species, the females being much 

 larger and more dilated posteriorly than the males. The species is contained in most 

 collections, and easily recognized by the uniformly testaceous elytra, which have only 

 the sutural and lateral margins narrowly bluish black. In the figured specimen a 

 number of obscure spots have been drawn, which are only visible in specimens in which 

 the elytra have through some cause been discoloured. 



2. Leptinotarsa chalcospila. (Tab. XIII. fig. 9.) 



Leptinotarsa chalcospila, Stal, Diagn. 1858, p. 476; Monogr. Chrys. Amer. p. 157 \ 

 Hab. Mexico 1 . 

 Of the same size as L. cacica, but each elytron with from seven to ten spots placed 



2g2 



