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Show 1880.] PROF. WESTWOOD ON THE GENUS PERGA. 359 1. A Monograph of the Sawllies composing the Australian Genus Perga of Leach. By J. O. WESTWOOD, M A F.L.S., &c. [Received March 16, 1880.] (Plates XXXIII.-XXXVII.) Family TENTHREDINID.E. Genus PERGA, Leach, Zool. Miscell. iii. p. 115. Antennce breves vel brevissimce, 6-articulatee (rarius 7-, rarissime b-articulatce), articulo ultimo clavam efformante. Labrum par-vum, subsemicirculare. Clypeus distinctus, transversus, antice scepe emarginatus. Mandibular validce, arcuatce, dimidio basali lato, in medio dente vel incisione parva angulata instructor; apice acutee. Palpi breves, subcsquales, maxillares 4-articulati, labiates 3-articulati. Collare utrinque in squamam magnam lateralem productum. Alee latce, cellula unica marginali apice appendicular, cellulisque 4 submarginalibus, stigmate magno, margine alarum anticarum pone stigma in maribus scepe dilatato et oblique truncato ; venulis inter cellulas marginales scepe medio bullatis. Tibice 4; posticee in medio lateris interni spiuula armatee, apiceque bicalcaratce, calcaribus mediocribus acutis simplicibus. ' The fine species of this genus are natives of Australasia, where they represent the Cimbeces of the northern hemisphere. They are represented also in South America by the species of the genus Pachylosticta, which, both in their metallic colours and the curious structure of the dilated fore wings, offer a complete analogy to the Pergce. With the exception of the Cimbeces, they are the largest known species of Sawflies ; and several of the species even rival the larger species of Cimbex (which are the giants of the family) in size. The antennae 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. In one species they are even deficient of one of the intervening joints, being only 5-jointed (Perga mayrii), whilst in several of the species (P. leachii, jurinei, and halidaii) the basal portion of the terminal clavate joint 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 maxillae and labium, with the palpi, are short and united into a mass by basal membrane, as shown in Plate X X X I I I . figs. 2 and 3-the inner lining (fig. 3), and also apparently the outer connecting skin of these organs being apparently continuous and not exhibiting any |
