Rev. F. 1). Morice's Notes on Australian Sawflies. 327 



that in both rases the peculiarity was inherited from 

 Arctogaeic ancestors common to both groups, who have 

 bequeathed it to some, but not to all, of their descendants. 

 However explained, it seems a curious fact that Perga and 

 Xyloperga spp. (at least in all such specimens as I have 

 been able to examine) should differ in this character, for 

 apart from it the two genera are so closely allied that 

 it may be doubted whether we do right in separating 

 them. 



I think that we must consider the 6- and 4-jointed con- 

 dition to be the primitive one, but that it is useless to spend 

 much thought on the question, why such and such forms 

 have departed from it. Had the modification anything 

 to do with any peculiarity in the feeding-habits of such 

 genera as possess it, it would have surely extended to 

 Xyloperga as well as Perga. At that we may be content 

 to leave it ! 



(e) The spinose tibiae of so many Australian imagines 

 are a character which is not easily accounted for. It is 

 an extremely rare character in Arctogaea : in fact, apart 

 from the Pamphilinae, it seems to be limited in the Holarctic 

 region to one genus, namely Arge. In Notogaea, however, 

 besides occurring (as might be expected) in the three 

 genera which are manifestly Arginae, it is found also 

 in Perga, Xyloperga, Phylacteophaga, Philomastix, and 

 Cerealces. In Neogaea, again setting aside genera of 

 Arginae, tibial spines (apart from the apical " calcaria," 

 are found in Syzygonia and Incalia which are in other 

 characters closely allied to Perga and Cerealces. but not in 

 Pachylosticta (which is in many ways a PergaAike form). 

 Tibial spines occur also in several genera belonging to 

 groups which, as Mr. Rohwer has lately suggested (Ann. 

 and Mag. Nat. Hist., November 1918), may probably be 

 allied to the Arginae, and also to the Australian Ptenjgo- 

 phorus. But I do not think that so large a proportion of 

 Neogaeic, as of Notogaeic genera possess them. Nor do 

 I at present feel able to draw any particular inferences 

 from these facts as to special affinities between Notogaeic 

 and Neogaeic groups unless (e.g. those which Konow calls 

 Syzygoniides) they agree in a. considerable aggregate of 

 other characters. 



It may be remarked that spinose armature of the legs 

 is a very frequenl character in Hymenoptera other than 

 Sawflies, and serves among these many purposes (e.g. in 



TRANS. EX T. SOC. LOND. 1918. — PARTS III,IV. (mAR.'19) Z 



