Ftir Darwin. 



3. That, as in the Crustacea, the sexual orifice and anus are placed upon 

 different segments; "whilst the former is situated in the ninth segment, the latter 

 occurs in the eleventh" (Gerstacker). 



4. Their palaeontological occurrence; "in a fossil state the Orthoptera make 

 their appearance the earliest of all Insects, namely as early as the Carboniferous 

 formation, in which they exceed all others in number" (Gerstacker). 



5. The absence of uniformity of habit at the present day in an order so 

 small when compared with the Coleoptera, Hymenoptera, <S:c. For this also is 

 usually a phenomenon characteristic of very ancient groups of forms which have 

 already overstepped the climax of their development, and is explicable by extinction 

 in mass. A Beetle or a Butterfly is to be recognised as such at the first glance, 

 but only a thorough investigation can demonstrate the mutual relationships of 

 Termes, Blatta, Mantis, Forficula, Ephemera, Libellula, &c. I may refer to a 

 corresponding remarkable example from the vegetable world : amongst Ferns the 

 genera Aneimia, Schizcea and Lygodium, belonging to the group Schizceacece which 

 is very poor in species, differ much more from each other than any two forms 

 of the group Polypodiacece which numbers its thousands of species. 



If, from all this, it seems right to regard the Orthoptera as the order of 

 Insects approaching most nearly to the common primitive form, we must also 

 expect that their mode of development will agree better with that of the primitive 

 form, than, for example, that of the Lepidoptera, in the same way that some of 

 the Prawns (Peneus) approaching most closely the primitive form of the Decapoda, 

 have most truly preserved their original mode of development. Now, the majority 

 of the Orthoptera quit the egg in a form which is distinguished from that of the 

 adult Insect almost solely by the want of wings; these larvae then soon acquire 

 rudiments of wings, which appear more strongly developed after every moult. 

 Even this perfectly gradual transition from the youngest larva to the sexually 

 mature insect, preserves in a far higher degree the picture of an original mode 

 of development, than does the so-called complete metamorphosis of the Coleoptera, 

 Lepidoptera, or Diptera, with its abruptly separated larva-, pupa- and imago-states. 



The most ancient Insects would probably have most resembled these wingless 

 larvae of the existing Orthoptera. The circumstance that there are still numerous 

 wingless species among the Orthoptera, and that some of these (Blattidce) are so 

 like certain Crustacea (Isopods) in habit that both are indicated by the same name 

 ("Baratta") by the people in this country, can scarcely be regarded as of any 

 importance. 



The contrary supposition that the oldest Insects possessed a "complete meta- 

 morphosis", and that the "incomplete metamorphosis" of the Orthoptera and 

 Hemiptera is only of later origin, is met by serious difficulties. If all the classes 

 of Arthropoda (Crustacea, Insecta, Myriopoda and Arachnida) are indeed all 

 branches of a common stem (and of this there can scarcely be a doubt), it is 

 evident that the water-inhabiting and water-breathing Crustacea must be regarded 

 as the original stem from which the other terrestrial classes, with their tracheal 

 respiration, have branched off. But nowhere among the Crustacea is there a mode 

 of development comparable to the "complete metamorphosis" of the Insecta, nowhere 

 among the young or adult Crustacea are there forms which might resemble the 



