GENERAL REMARKS. 1^1 



find opposite views expressed in regard to the rank 

 of metamorphoses, and these may confuse them unless 

 explained. He speaks, on page 41, of the maggots 

 of flies as belonging ''' to a lower grade " of metamor- 

 phoses than the grubs which have biting mouth parts 

 and heads, and of the caterpillar as on a higher level 

 than the vermiform larvae of Diptera and Hymenop- 

 tera. This, literally translated, means that larvae, like 

 those of the grubs of most Coleoptera and Lepidop- 

 tera, have heads, mouth parts, and legs which have 

 not yet suffered from reduction ; but in speaking of 

 these as " lower grade," Lubbock makes a mistake 

 in systematic perspective. If, as he holds, the sec- 

 ondary larvae are all primarily the outcome of the 

 Thysanuran form, they are all what he ought to call 

 "higher grade," being more speciaHzed and farther 

 removed from this primitive insect standard than the 

 larvae of the more generalized or first series of orders. 

 The same and, we think, more philosophical mode of 

 dealing with the facts leads to the corollary that among 

 themselves the larvae of the more specialized orders 

 are really "higher," if the use of this word is consid- 

 ered essential, or more specialized in proportion to 

 the extent of their structural deviation from the Thy- 

 sanuran standard. Thus the larvae of Diptera are, as 

 a rule, more specialized than any other, and have to 

 be set on the extreme left in our table on this 

 account. The words "higher and lower grade" are 

 extremely confusing, since they embrace three diff"er- 

 ent classes of ideas, — anatomical and physiological 

 facts and teleological notions. Nature leads us along 

 Hues of modification which sometimes rise through 



