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



Plate 139, Figs. 1-4. 



OPSOMALA SORDIDA (Aud. Serv.). 

 The Dusky Flat-horned Locust. 



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

 Orthoptera. Section Saltatoria. Family Acridida?.) 



Gen. Char. — Head large, conoidal, front extended in a horizontal, thick, conical point 

 between the antennas ; anterior face extending very obliquely backwards and downwards, with 

 four slender longitudinal keels, two close together in the middle, arising between the antennae ; 

 the other pair, one on each side, arising between the eye and antenna? ; eyes very large, promi- 

 nent, placed obliquely near the anterior top of the head, close to base of antenna? ; ocelli three, 

 one in middle between the two keels, and one on each side above the base of the antenna? in 

 front of the eyes ; antenna? nearly as long as head aud thorax, of numerous (about 23) joints, 

 ensiform, with flattened upper and lower sides, usually widening abruptly from the third joint, 

 and taperiug to the end. Prothorax indistinctly tricarinate, with three or four transverse sulci, 

 narrow, rounded above, slightly compressed, rounded or obtusely angular behind ; presternum 

 with one strong acutely conical spine in the middle; mesosternum and metasternum very broad, 

 flat, and smooth ; elytra narrow, lanceolate, rounded at tip, usually longer than the abdomen ; 

 wings slightly shorter than the elytra. Abdomen large, unicarinate above ; appendages small. 

 Legs : anterior and middle pairs small ; posterior ones longer than the body, with thickened 

 femora, and two rows of spines on distal half of tibia? ; tarsi slender, last joint elongate ; 

 cushion between the claws large.] 



Description. — Female: Head and prothorax rugged, with granules, irregularly 

 arranged in longitudinal rows; mesial keel on head and prothorax small, slightly 

 marked; lateral keels on prothorax indistinct; transverse sulci on thorax small, the 

 two posterior reaching the lateral margin, the two anterior shorter; prothorax 

 transversely rounded, with an obtuse mucro behind ; antennae flattened, of 23 joints. 

 Color: Head, thorax, anterior four legs, and abdomen dull brown, with tinges of 

 bluish-grey; face and antennae grey ; hinder thighs mottled grey and cream color 

 externally, dark greyish-blue on inner side; hind tibiae pale testaceous red on inner 

 side, paler on outer side, with the two rows of spines nearly black. Tegmina 

 moderately translucent, very pale brownish-grey, with brown veins and numerous 

 irregular, ill-defined, quadrate spots of dull pale brown ; wings colorless, or with 

 tinge of bluish-grey towards inner angle, with fine brown veins; abdomen smooth, 

 glossy, of a richer brown than the body, and with cloudy patches of grey on hinder 

 segments ; upper pair of ovarian plates granulated, light cream color, with a strong 

 median keel ending in the dark, pointed extremity; lower pair smoother, punctated, 

 bicuspid, points dark ; appendages very small. Length from frontal conical point to 

 end of abdomen, 2 ins. 5 lines. Comparative measurements to length, taken as 

 100 : Head, J-fo ; prothorax, y 1 ^ ; antennae, -££■$ ; tegmina, y^ ; width of teg- 

 mina, -^ ; length of wings, -j r ^; hind femur, fifc; hind tibiae, j-fo ; hind tarsi, 

 T \j%. Male: Similar to female, but much smaller; the upward curved sub-anal 

 plate very large; appendages moderately long. The spotting of the tegmina darker 

 and more distinct. Length from frontal point to end of abdomen, 1 in. 4 lines; 

 proportional length of head, y 1 ^ ; prothorax, y 2 ^ ; tegmina, y^y ; hind thigh, -f'^ ; 

 antennae, T 4 ^. Pupae, 1 in. 2 lines long, have the wings 2 lines long; no ocelli; 

 and the surface of the abdomen very rough, with longitudinal branching vermicular 

 ridges, granules, and puncta. 



Reference. — Audinet Serville, Orthop., p. 592. 



Vol. II— Decade XIV.— y. ' 151 



