ORTHOPTERA. Ill 



sanuriform stage is distinctly shown. In the still more 

 specialized forms, Mantidae, Phasmida^, and the Salta- 

 torial families, these stages are accelerated or absent, 

 and the young when born are more like the adults, 

 or have usually more specialized proportions in the 

 parts of the body, etc., than in the larvae of cock- 

 roaches. Some writers, notably Balfour, have supposed 

 that protection of the ova produced such results, but 

 the ova in some genera of the Phasmidae are dropped 

 upon the ground and exposed through two winters 

 and one summer without protection of any kind. Such 

 types as the three groups just mentioned are commonly 

 brought forward as fatal objections to the derivation 

 of insects from a form similar to Thysanura. The 

 young locust when hatched has enormous leaping-legs, 

 a body which is short in proportion, and a large head 

 and thorax like the adult. There are no signs whatever 

 of a Thysanuran ancestry in the larvae except the ab- 

 sence of wings. It is obvious that the large leaping- 

 legs, the head with its peculiar pose, and the characters 

 of the thorax have been formed before the animal could 

 have had any use for them, before, indeed, it was out 

 of its egg-case. No one can deny that the pecuHari- 

 ties of the hind-legs are adaptive ; and their presence 

 at such early stages, before they can be used by the 

 animal, shows that their reproduction in the young of 

 existing saltatorial forms is due to inheritance. The 

 affinities of the saltatorial forms of Orthoptera, with 

 the generalized Orthoptera (Cockroaches), are shown 

 in obvious characteristics ; and this great difference 

 in development is accounted for, according to our 

 mode of viewing the problem, by a law of heredity 



