1880.] PROF. WESTWOOD ON THE GENUS PERGA. 35^ 



1. A Mouogi-aph of the Sawilies co!ii.jasmg the AustiMliaii 

 Genus Perga of Leach. By J. O. Wu^r.vooy, M.A., 

 E.L.S., &c. 



[Eeceived Marck 1(5, 1880.] 



(Plates XXXiri.-XXXVII.) 



Family Tenthredinid-s. 



Genus Perga, Leach, Zool. Miscell. iii. p. 115. 



AntenncB breves vel brevissimce, 6-articulatce (rarius 7-, rurissime 



5-articulat(e), articulo ultimo clavam ejformaiile. Labruni par- 



vum, subsemicirculare . Clj/peus dist'utctas, trunsversus, antice 



scBpe emarginatus. MaiidibulcB validue, arcuatce, diniidio basalt 



lato, in medio dente vel incisio/ie parva anjulata instructs ; 



apice acutce. Falpi breves, subcequales, maxillares 4-articulati, 



labiales 3-articulati. Collare ittrinque in squamam magnam 



lateralem productuni. Alee latce, cellula uiiica marginali apice 



appendiculalo, cellalisque 4 submarginalibus, sligmule magtio, 



margiiie alarum anticarum pone stigma in maribus scepe dilatato 



et oblique truiicato ; veaulis inter cellulas maryinales scepe medio 



bullaiis. Tibice 4; posticce in medio luteris interni spinula armatce, 



apiceque bicalcaratce, calcaribus mediocribas aculis simplicibus. 



The fine species of tliis geims are natives of Australasia, where 



they represent the Cimbeces of the northern hemisphere. They are 



represented also in South America hy the species of the genus 



Piichylosticta, whicii, both in their metallic colours and the curious 



structure of the dilated fore wings, offer a complete analogy to the 



FergcE. 



With the exception of the Cimbeces, they are the largest knowa 

 species of Saw flies; and several of tiie species even rival the larger 

 species of Cimbex (which are the giants of the family) in size. 



The antennEe are very short and clavate, in a few of the species 

 scarcely extending as far as the eyes ; they are inserted on the 

 outer margins of two frontal tubercles. Li one species they are 

 even deficient of one of the interveniug joints, being only 5-jointed 

 {Perffa mayrii), whilst in several of the species (P. leachii, jiirinei, 

 and halidaii) the basal portion of the terminal clavate joiut is 

 distinctly articulated, making the organ 7-jointed. I have not 

 thought it advisable to separate these species generically from the 

 rest. 



The mouth of the species in this genus offers some peculiarities 

 hitherto not noticed. The mandibles are strong and horny, the 

 apical half curved and acute at the tip, the basal portion flattened, 

 terminating on the inner edge in a deep simple incision. The 

 maxillse and labium, witii the palpi, are short and united into a mass 

 by basal membrane, as shown in Plate XXXIIL figs. 2 and 3 — the 

 inner lining (fig. 3), and also apparently the outer connecting skia 

 of these organs being apparently continuous and not exhibiting any 



