*^28 [September 



them." But by this mode of arguing in a circle we may prove that 

 no conceivable amount of divergence, that does really occur in a given 

 species, is a divergence from nature. 



From what Agassiz says, as to the " close adherence to the distinct, 

 well-defined and iuviiriable limits of the species", in wild species as 

 contra-distinguished fi'om domesticated ones, {Math. Stiuly^ p. 145,) 

 any one not familiar with Natural History would infer, that wild spe- 

 cies, in the same geographical locality, scarcely vary at all from the 

 normal type. Every field-entomologist knows that, in many species of 

 insects, this is not so. To illustrate from one single Order, Coleoptera : 

 — Arrh-'iioiles sepfentrioiiis Hbst. and (htogeiius ru/m Fabr., vary ex- 

 ceedin<i:ly in size, so that some individuals are full twice as lono- as 

 others, and in the male of the former of these two species the suout is 

 sometimes full as broad as long, and sometimes on the other hand 

 full twice as long as broad, whence some foreign entomologists have 

 been led to consider the varieties as distinct species. But as nu- 

 merous intermediate grades occur in all these cases in company with 

 each other, it is evident that the diflPering forms are mere varieties. 

 Again, as regards the variable length of what are commonly called 

 horns in insects, I have % specimens of Phanaeus carni/ex Lin. with 

 the horn that proceeds from the vertex three times as long as in other 

 specimens, with all the intermediate grades; and the length of the tho- 

 racic horns in % PheUidius (Jjuletophagus) cornufus Fabr. and of the 

 mandibles in % Lucanus efaphus Lin. is almost equally variable. Fi- 

 nally, to give a few examples of colorational variation, in Haltlca strio- 

 lata Fabr many individuals occur with the pale elytral vitta resolved 

 into two roundish pale spots, so that Fabricius described them as a dis- 

 tinct species under the name of hipushdata. In Haltlca aUernata Illig. 

 some specimens have the normal 5 black vittae on the elytra, and some 

 have perfectly immaculate elytra, with all the intermediate grades. In 

 Cerotoma camincd Fabr. some specimens have the two normal dis- 

 coidal black spots of each elytrum confluent so as to form a black vitta, 

 and I have a single specimen with the elytra entirely immaculate ex- 

 cept the triangular black spot on the seutel, and a similar one with 

 faint traces only of the normal markings ; and analogous variations 

 occur in (Edlonychis quercata Fab., (E. Q-macidata Hlig. and Blepha- 

 rida rhois Forst. In Melasoma (Una') interrupta Fabr. some spe- 



