200 Mr. J. O. Westwood's Description 



garded as distinct species, to be considered as such. The cele- 

 brated physiologist, Spallanzani, in 17G8, published a Memoir, 

 containing suggestions for the instituting of experiments for the 

 production of hybrid insects, with a view of solving the grand 

 problem of generation, which at that period attracted a great 

 share of attention amongst philosophers. His memoir is entitled 

 ** Invito a intraprendere sperienze, onde averre muletti nel popolo 

 degl' insetti per tentar di scogliere il gran problema della gene- 

 razione." A copy of this scarce tract is in the library of the 

 British Museum. 



Burmeister (Manual, p. 515) observes, that " it is uncertain whe- 

 ther such mixtures as those detailed above have been productive, but 

 from analogy with the superior animals we might say no ; should, 

 liowever, the copulation of closely allied species actually produce 

 young, these would not be able to unite productively, as is proved 

 by the general rule of analogous instances in the superior animals, 

 yet this, even, is not without an exception. Hence, Gravenhorst's 

 opinion, that from such bastard copulations of allied species many 

 new forms originate, must be totally rejected, exclusive of the 

 view that in case of such a course in nature its beautiful regu- 

 larity and order would speedily terminate in illimitable confusion, 

 of which, however, there is not the least proof." Now the circum- 

 stances recorded by Mr. House enable us to see the extent to 

 which these observations of Dr. Burmeister are applicable. We 

 thus perceive that the copulation of two distinct species of insects 

 is productive — and not abortive — that the progeny of such an 

 union, between two closely allied species, partakes of the specific 

 characters of both species, but that the sexual power is ren- 

 dered obsolete, and that it is not, except by some rare accident 

 against nature, that such an union takes place. Marsham, how- 

 ever, observes, in the Entomologia Britannica (p. 169), " Ex 

 coitu Coccinellarum inter omnes familias promiscuo, varietates 

 plurimas ortse sunt;" whilst M. Boisduval, on the other hand, in 

 his Monograph in the Zygcemdce (p. 5), states, that he had often 

 found Zygcena Jilipcndulce in copula with Z-jieucadani, and Zj/gcena 

 trifolii with Hippocrepidis, that the females had subsequently laid 

 eggs, but these had never hatched, (a circumstance contrary to 

 the observation of M. De Villiers, cited above). He adds, how- 

 ever, " il est possible cependant que quelques uns eclosent dans 

 la nature." In like manner M. Audouin instituted various ex- 

 periments upon Coccinella hipunctata and C. dispar, which are often 

 found coupled, but the eggs produced by the female have always 

 proved sterile, a circumstance which he had noticed as many as 



