Zoology. - ] NATURAL HISTORY OF VICTORIA. [Insects. 



Plate 140. 



TROPINOTUS AUSTRALIS (Leach). 



The Cinnamon Keel-backed Locust. 



[Genus TROPINOTUS (Aud. Serv.). (Sub-kingdom Articulata. Class Insecta. Order 

 Orthoptera. Section Saltatoria. Family Acridida;.) 



Gen. Char. — Head large, elongate ; anterior face narrow in front, with flat converging 

 sides, vertical, with two longitudinal approximate keels in the middle and one other on each 

 side ; front projecting forward between the antenna? in a sligbtly acute tbick cone. Eyes oval, 

 not very prominent ; antennas shorter than thorax, thick, of about 20 slightly flattened joints, 

 arising very close together, filiform ; palpi of slender joints. Thorax strongly compressed above, 

 inversely boat-shaped, with a very large, median, dorsal, compressed, arched keel, extending in 

 front over the head in a point, and from the metathorax in a point behind over the elytra 

 beyond the base of the wings, the anterior and posterior lateral margins converging obliquely 

 to those points, the posterior very acutely; presternum small, with one central, long, acutely- 

 conical spine in middle, sometimes bifid at tip ; meso- and meta-sternum very broad, flat, smooth. 

 Elytra a little longer than the abdomen, with fine ueuration ; wings ample, a little shorter than 

 the elytra. Abdomen large, with a strong, dorsal, median keel ; appendages short, setaceous ; 

 sub-anal plate of male large, curved upwards, convex, triangular tip extending beyond the abdo- 

 men. Posterior legs large, thighs moderately thickened, with chevron marks on side ; tibia?, 

 except at base, with two equal rows of tooth-like spines ; tarsi 3-jointed; pads between claws 

 small ; maxillary palpi of 5 joints ; labial palpi of 3 joints ; maxilla? tridentate. South America, 

 South Africa, and Australia.] 



Description. — Female : Length from front of head to end of abdomen, 1 in. 

 9 lines. Proportional measurements to length (taken as 100): Length of head, 

 ffo 5 Pi'othorax, ^ ; teg-mina, ^ ; wings, J^L ; antennae, ^ o ; hind thigh, ^ ; 

 hind tibiae, y^ ; width of teg-mina, ^oq- Head and thorax minutely and irregularly 

 granulated. Antennas of 23 joints, less than half the length of head and thorax. 

 Elytra considerably longer than abdomen, narrow, oblong-, obliquely truncated at 

 distal end, translucent, but not so transparent as the wing-s, minutely netted. 

 Color : Whole body, head, thorax, abdomen, leg-s, and elytra, lig'ht, dull cinnamon- 

 brown, with minute, scattered, blackish speckles; wings with veins of the same 

 color, and the membrane a little lighter and more pale yellowish-tawny at base, the 

 anterior costal portion nearly like the teg-mina. Legs and tarsi paler. Male: Like 

 female in size, shape, and color, except the large sub-anal plate and longer lateral 

 appendages. 



Reference. — Grylkis Australia, Leach, Zool. Misc., v. i., p. 56, t. 24 = Trojifc- 

 notus cinnamonicus, Serv., Hist. Nat. des Insect. Orthop., p. 620. 



The Tropidonoti, or keel-backed Locusts, differ from ordinary 

 Locusts in the great compression of the midline of the thorax into 

 a high-arched prominent keel, extending over the head in front and 

 over the base of the abdomen behind, from which the genus derives 

 its name. The single median spine of the presternum, and the 

 great compression of the narrow-keeled face in front, and the 

 angular frontal projection of the head, are also peculiar character- 

 istics of these insects, in which they approach the Truxal% or 



Vol. II.— Decade XIV. -z. [ 155 ] 



