37 



COLLECTED OBSERVATIONS ON BRITISH SAWFLIES. 

 By ihe late Edward Newman. 



(Continued from vol. ix. p. 07.) 



There are, then, two very distinct kinds of resemblance, 

 which I would call endomaeous and extorageous. The first 

 relates to internal and intrinsic characters; frequently, but 

 not necessarily, also to habits, economy, and food. The 

 second only to external or superficial characters ; those 

 characters which are the first to strike the eye and the mind 

 of him who applies eye and mind to the subject. I will give 

 an instance of this in each of the three great tetrarchies of 

 Endosteates. 



In sucklers the resemblance between the flying phalanger 

 {Petaurus) and the kangaroo [Macropus) is endomteous, but 

 between the flying phalanger {Phnlanyisla) and flving squirrel 

 {Pteroniys) it is extomaeous. I omit to mention the birds 

 because the natural distribution of that class has not received 

 the searching investigation of science. In reptiles the 

 resemblance between the newt {Triton) and the frog {liana) 

 is endomaeous; that between the newt and the lizard 

 (Lacerta), extomaeous; although the similarity of form is so 

 exact thatLinnaeusplaced them in the same genus, calling them 

 Lacerta agilis and L. paliisiris ; and as regards our British 

 reptiles he made them consecutive. In fishes the resemblance 

 between the eel {Anguilla) and the muraena {Murcena) is 

 endomajous; indeed so nearly are they alike in structure 

 that ichthyologists place then) in the same family. On the 

 other hand, the resemblance between the muraena and the 

 lamprey {Petroniyzon) is entirely extomaeous; it is external, 

 although so close as to deceive all but the educated eye of 

 science. This external, or extomaeous, resemblance has long 

 been familiar to naturalists, and has been utilised with the 

 view of substantiating a host of hypotheses, in some of which 

 it is called protective : it is the relation of affinity and 

 analogy so eloquently advocated by Mr. W. Macleay. 



Another observation seems absolutely necessary, that is to 

 caution the inexperienced reader against supposing that the 

 boundaries of groups are rigidly defined in Nature. Two 

 centuries ago the innnortal Ray told us this was not the case. 

 He says: — "As Nature never passes from one extreme to 

 another, except by something lying between the two, so she 

 is accustomed to produce creatures of an intermediate and 

 doubtful character which partake of both extremes, and so 



