THE CAEBONIFEEOUS AGE. 137 



pions and spiders, very like those of the modern 

 world, have been found in the coal measures, both in 

 jEurope and America ; so that while we know of no 

 enemy of the Devonian insects except the fishes, we 

 know in addition to these in the Carboniferous the 

 spiders and their allies, and the smaller reptiles or 

 batrachians to be noticed in the sequel. With refer- 

 ence to the latter, it is a curious fact that one of tho 

 first fragments of a winged insect found in the coal- 

 fields of America was a part of a head and some other 

 remains contained in the coprolites or excrementitious 

 matter of one of the smaller fossil reptiles. It is 

 perhaps equally interesting that this head shows one 

 of the compound facetted eyes as perfectly developed 

 as those of any modern Neuropter, a group of insects 

 remarkable even in the present world for their large 

 and complex organs of vision. We may pause here -to 

 note that, just as in the Primordial we already have 

 the Trilobites presenting all the modifications of which 

 the type is susceptible, so in the Carboniferous we 

 have in the case of the terrestrial articulates a similar 

 fact highly specialised forms like the beetles, the 

 spiders, and the scorpions, already existing along 

 with comprehensive forms like the millipedes. Let 

 us formulate the law of creation which the Primordial 

 trilobites, the Devonian fishes, and the Carboniferous 

 club-mosses and insects have taught us: it is, that 

 every new type rapidly attains its maximum of de- 

 velopment in magnitude and variety of forms, and then 

 remains stationary, or even retrogrades, in subsequent 



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