146 BRITISn APHIDES. 



that the earliest insects did not possess wings com- 

 posed of simple membranes. Mr. S. H. Scudder comes 

 to the conclusion that the front and hind wings of 

 Palaeozoic Insects were similar ; and that membranous 

 heterogenity made its appearance in Mesozoic times.* 



Our ignorance of the steps in a natural process need 

 be no barrier to an hypothesis, if it be supported on 

 reasonable evidence, or even analogy. Whether che- 

 mical and other forces were more active in geological 

 times may be a point for discussion. Life under ex- 

 citement is usually intensified, but perhaps at the cost 

 of duration. Under extreme surroundings we mio-ht 

 suppose intermediate links quickly filled up; or at 

 that distant period they might overlap and produce 

 modifications too rapid, for us to follow. Time doubt- 

 less is an important factor, and we are liable to consider 

 an event marvellous or otherwise in proportion to the 

 time consumed in its production or disclosure. 



For instance, the effects involved in the alteration in 

 brilliance of one whole magnitude of a well-known 

 star in our system, in the course of two days and a 

 half, might appear to us little short of miraculous, if 

 we could so live as to see them. 



The fragmentary condition in which fossil insects 

 are commonly found renders their examination difficult. 

 Several Continental observers have done good work in 

 this direction ; but the investigations in England are 

 comparatively scanty. To Mr. H. Goss's papersf on 

 " Fossil Entomology" I am indebted for many details ; 

 and also to Mr. S. H. Scudder for his numerous memoirs 

 on the fossil insects of America. 



Professor Hacckel, with his usual bold stroke of 

 hypothesis, supposes that the very ancient Zoopoda 

 have been the ancestral forms of the Crustacea, and that 



* « Early Typos of Insects,' Samuel H. Scudder, 1879, p. 21. N.B.— 

 Mr. Scudder has pointed out to me that in my introductory remarks in 

 vol. iii on the antiquity of insects I Lave not given sufficient antiquity 

 (<> the Homoptera. I am glad to be corrected by so able an authority. 



f " Introductory Papers on Fossil Entomology," by H. Goss, 'Ent. 

 Mon. Mag.,' vol. xv, p. 52, rt acq. 





