Rev. F. D. Morice's Notes on Australian Sawflies. 331 



Paraperga (Type jticunda), and Neoperga (Type amenaida), 

 are " synonyms " of Xyloperga, Shipp ! 



Konow in his unfinished Monograph, and also in Genera 

 Insectorum, divides the group into two genera, viz. Perga 

 and Heptacola. The latter name must sink as a synonym 

 of Xyloperga; and the author also fell into a mistake by 

 commencing his list of Heptacola spp. with macleayi, 

 Westw. That species, as I have remarked elsewhere, is 

 really a Philomastix. 



In concluding these remarks, I would suggest that, 

 even when a genus can be divided into more or less definite 

 sections, it does not follow that it is well to name such 

 sections, and still less to erect them into " Genera." The 

 study of any natural group is, no doubt, advanced in one 

 direction if we can detect and point out unnoticed differ- 

 ences between the sections into which (like all other natural 

 groups) it is divisible. But in another direction it is 

 impeded, if such stress is laid on these differences as to make 

 us forget the not less important differences which separate 

 the group as a whole from other groups. If the object of 

 Systematica were merely to facilitate the naming of speci- 

 mens, it would be only a question of practical convenience 

 in each case, whether at such and such a time this or that 

 genus should be upheld or disintegrated. But, if our 

 ideal be rather a classification corresponding as nearly as 

 our knowledge permits to the actual proportion of likeness 

 as well as of unlikeness existing between the objects we 

 are studying, I venture to think that, whereas a single 

 character may suffice to isolate some one form as a " good 

 species," much more than this — in fact, a considerable 

 aggregate of characters peculiar to some one section of a 

 group (and also some reason for considering them possessed 

 of phylogenetic significance), should be j)roducible, before 

 we are justified in treating that section as a " Genus." It 

 is true that we can never hope to establish categories of 

 classification which shall fully • represent the degrees of 

 consanguinity between related organisms. But still that 

 should be the ideal at which we aim, and if we aim at it. 

 we shall hesitate before we decide to call that a generic 

 difference which can scarcely be distinguished from another 

 which we call specific 



