INSECT. 



groups or individuals, and never any interval between 

 them, I think we are going further than either obser- 

 vation or analogy will warrant. Were this really and 

 strictly the case, it seems to follow that every group 

 or individual species must, on one side, borrow half 

 its characters from the preceding group or species ; 

 and on the other, impart half to the succeeding. 

 (Query, whether every real species or group has not 

 some one or more peculiar characters, which it neither 

 derives from its predecessor nor imparts to its suc- 

 cessor in a series ?). But one of the most evident 

 laws of creation is variety, and if we survey all the 

 works of the MOST HIGH, we shall nowhere discover 

 that kind of order and symmetry that this strict inter- 

 pretation implies. The general march of nature, 

 therefore, seems to say, that there must be varying 

 though not violent intervals in the series of beings, 

 or, in other words, some conterminous species or 

 groups have more characters in common than others." 

 Very few words will suffice upon the nature of 

 species, a term employed to designate those groups 

 of animals which (save as respects sexual distinctions) 

 possess a perfect conformity in their characters, which 

 indeed they have uninterruptedly possessed since the 

 first establishment of species. The oldest records of 

 natural history, where sufficiently clear to be relied 

 upon, show us that in the species which are therein 

 described or figured, not the least variation has taken 

 place in them. Were not this the case, indeed, there 

 would be grounds for the belief that there are new 

 species of animals produced, which, as Ray says, 

 would certainly now and then, nay very often, happen 

 were there any such thing. But, as in the higher 

 animals, the species of insects are liable to variation, 

 as every collector is well aware ; thus, some moths, 

 which have the ground of their wings of a pale colour 

 with dark markings, will be found to have dark wings 

 with light marks. Variations in size are equally 

 common, and entomologists deem it expedient to 

 retain in their collections suites of individuals of each 

 variable species, from the smallest to the largest ; 

 sometimes, indeed, the latter are many times larger 

 than the former, a circumstance often occurring in 

 wood-feeding insects. In general also male insects 

 are much smaller than the females. The reader will 

 also bear in mind that this variation in size is not the 

 result of increased growth after arrival at the winged 

 state, and that the small individuals will by and bye 

 attain the size of their partners. This is quite con- 

 trary to every principle of insect physiology. It is 

 in the larva state that the eating and growing of these 

 animals chiefly takes place. And it would be as 

 requisite for the imago to cast its horny envelope in 

 order to increase its size, as it is for the larva to do 

 the same thing ; again, it must be self-evident that 

 without the sloughing, the external envelope^ could 

 never, from its consistence, undergo the slightest 

 change. Moreover, the change which the digestive 

 organs undergo in the passage from the larva to the 

 imago states, sufficiently proves the same fact. But 

 species often vary even in structure, not indeed in 

 any of the more important organs, but in the various 

 arms with which they are furnished. This is espe- 

 cially the case with the cornuted species, and those 

 which have the mandibles very greatly developed. 

 Here in many instances there appear to be a series of 

 individuals intermediate between the fully developed 

 species and the females, which are generally destitute 

 of these nppendagcs. This we have rtotu ed in many 



879 



species of lamelHcorn beetles, and in some of the 

 staphylinidae (Siagonium (juadricorne). The Rev. Mr. 

 Burrell also observed it in another species of the 

 same group, Itledius armatns, of which he describes 

 a variety with horns shorter than the head, although 

 usually longer, and which he is disposed to regard as 

 a neuter, an opinion also entertained by Mr. Haworth, 

 who considers that such neuters are far more frequent, 

 even in the hymenoptera, than hitherto imagined. 

 (Entomological Transactions.) Besides these, which 

 appear to be casual occurrences, there likewise exist 

 what have been termed permanent varieties in many 

 species, the individuals of which are found in situations 

 different from the ordinary type of the species, and it 

 has been considered that these variations have ori- 

 ginated somewhat in a similar manner to the varieties 

 of domestic animals ; but this may certainly be 

 doubted, because in most domesticated insects, the 

 common house-fly, disseminated as it is over the 

 whole surface of the globe, and the hive bee, we find 

 not the least liability to vary ; and if this be not the 

 case with these species, we can hardly attribute the 

 production of varieties in species, which are in nowise 

 subject to the rule of man, to a similar cause. 



The characters by which species are distinguished 

 are very variable, partaking indeed, in this respect, of 

 the peculiarities which we have noticed in our obser- 

 vations upon generic and sub-generic groups. In 

 very extensive genera the distinctions of species are 

 so minute, that it requires the most practised eye to 

 separate them ; and indeed there are some groups, the 

 species of which are so intricately blended together, 

 that no two entomologists are agreed as to their 

 distinctness. The genus Nothwpkilus (a genus of 

 small Carab'ul<E\ affords an instance of this. Until 

 very lately it was supposed to consist of only 

 two British species, Mr. Curtis, however, added 

 another; Mr. Waterhouse, increased the number to 

 eighteen, in a monograph published in the Entomo- 

 logical Magazine ; whilst Mr. Stephens has subse- 

 quently reduced this number to six. The characters 

 which supply specific distinctions are also very 

 variable, size, sculpture, colour, markings, locality, 

 general forms, are all employed, and it often happens 

 that a character, which in one group of insects would 

 be deemed of sufficient value to characterise a genus, 

 is in others only serviceable as a specific mark of 

 distinction ; thus in the genus Rhipicera (a group of 

 exotic beetles, with beautiful pectinated antenna)); 

 these organs vary in the number of their joints; 

 whereas we have seen, that in a whole section of 

 hymenoptera (Aculcata) the same number of joints 

 runs throughout the whole. 



In describing species of insects it is usual to give 

 a short character embracing the most striking charac- 

 teristics of tha species. This is ordinarily in Latin, 

 that language being universally regarded as peculiarly 

 adapted to science, being universally understood 

 wherever science exists ; indeed the neglect of this 

 plan, which we often notice in French and German, 

 and sometimes in English authors, shows a disregard 

 to a settled and most convenient custom, enabling per- 

 sons unacquainted with those particular languages to 

 identify, in some degree, a species, although the^ more 

 extended description may be written in either of these 

 or any other tongue. It is usual also to add the length 

 of the body and expansion of the wings, these admea- 

 surements being taken in inches and lines, which are 

 the tenth parts of an inch. 



