8 BEITISH APHIDES. 



outer cuticle into a crjstaline lens, with tlie subsequent 

 eangflionic elaboration of a retina, with its attendant 

 nerves, &c,, and throw all modification of form on the 

 adjacent surroundings ? * 



A similar question arises, whether the tendency in 

 Aphis to show supplementary wing -veins is a sign of 

 development or the contrary. f Activity and swift- 

 ness in f3ightarenot necessarily connected with breadth 

 of wing. The nervous energy of the higher Hymeno- 

 ptera gives strength to their flying organs, which, 

 though relatively small, are capable of much loco- 

 motive power. 



Again, shall we say that the lower Aphides are 

 degradations from Psylla, or improvements upon 

 Coccus ? 



Probably Sir J. Lubbock would hesitate to regard 

 the Apterous Aphis as a larva, in the ordinary sense ; 

 and therefore its inactive form will not bring exception 

 to his supposition, that larvae which live in circum- 

 stances which call for no locomotion, have relapsed into 

 the condition of their far distant vermiform ancestors. :[: 



In introducing these remarks upon these hypotheses, 

 we accept the conclusions simply as instalments, and 

 valuable contributions towards an abstruse and difiicult 

 question. 



If " Phantasie " or theory be an element in the 

 demonstration of true science, she must ever be a 

 handmaid, but never a mistress. Some thinkers, like 

 Professors Tyndall and Lankester, have boldly acknow- 

 ledged that philosophers are, and ought to be, largely 

 occupied with speculation and imagination. The 



* Examples in wticli the ti'ansparent corneal membrane is sliown to 

 be an expansion of the ectoderm or external cuticle may be seen in 

 PI. B, fig. 2; PL Xyil, fig. 4; PI. XXI, fig. 4; PI. XXII, figs. 4 and 5. 

 Some of these drawings show, also, how the optic nerve is in comunica- 

 tion with the oesophageal ganglion. 



t The excess or defect in the veining of the cubitus may be seen in 

 PL XXXV, fig. 3; PL LVII, fig. 2; PL LXYI, fig. 2; and PL XOVI, 

 fig. 5. 



X A slight tendency to the vermiform type, perhaps, may be traced 

 in the young underground inert larva of Pemphigus, see PI. CXII, 

 fig. U. 



