MIMICBY. 297 



Phasmidce almost prove the pre-existence of the Permian reptiles 

 and the Jurassic birds.* If these stick-insects really possessed, 

 and did not derive their imitative structure for protective pur- 

 poses, then the whole theory of " Protective Resemblance " 

 among insects may go to the wall. The need of protection 

 must undoubtedly have existed in Carboniferous times, if this 

 hypothesis is to stand, and such a view helps to prove, as 

 Huxley has already urged, a pre-Permian existence for reptiles,! 

 and, we may add, a greater antiquity also for birds, both of 

 which, we may presume, were, as now, great enemies to 

 insect-life. 



The only other explanation — known to the writer — which has 

 been offered to account for the peculiar structure of these Stick- 

 insects, is one proposed by the late Prof. Karl Semper, which 

 would have received additional emphasis had that naturalist been 

 aware (he at least does not allude to the fact) of the Phasma 

 being found as a Carboniferous fossil. Prof. Semper's pro- 

 position is that the structure denotes what has been styled 

 11 ' Larva-forms,' a name given to all animals which possess the 

 characters of the larvae of other species, and are nevertheless 

 capable of sexual reproduction." The opinion is amplified by 

 the following explanatory illustration : — " Thus species of the 

 same genera, perhaps even the very same species, in our damp 

 and cold climate, do not produce a new generation till they are 

 fully grown ; while in the dry warm region of the Mediterranean 

 they have produced two generations before they are fully grown."! 

 This would be somewhat on a line with the suggestion we have 

 made that most unicolorous animals are survivals from an original 

 assimilative colouration, and have thus survived by being in 



* These birds were, however, probably most divergent from present 

 avian types. Such an example is the Archceojpteryx of the Jurassic or 

 Oolitic epoch, which was not only furnished with teeth, but had a long 

 tapering tail, with other indications of reptilian affinity. 



f T. G. B., reviewing in ' Nature ' (vol. xlix. p. 196), ' Some salient 

 Points in the Science of the Earth,' by Sir J. W. Dawson, speaks of the 

 larger reptiles crawling over the soft mud, and leaving tracks in the coal- 

 fields of Nova Scotia, and remarks : "These discoveries came as a complete 

 surprise to the scientific world in days when few or no reptiles were known 

 of earlier date than the Permian." 



{ ' Nat. Condit. of Existence as they affect Animal Life,' p. 126. 



