104< Indian Museum Notes. [Vol. II. 



four specimens of Tryxalis turnta, Linn., (3) one specimen of Oxya velox 

 Burm., (4) one specimen of a species which is probably Epacromia dorsalis 

 Thumb., (5) one larva of a grass-hopper probably belonging to the genus 

 (Edalus. Of these the immature specimens are probably the " small 

 brown and green grass-hoppers, " alluded to by the Collector as present in 

 myriads, while the full-grown specimens o # f Pachytylus cinerascens are 

 likely to have been the " locusts " mentioned as present in comparatively 

 email numbers. Now, Pachytylus cinerascens is one of the chief migra- 

 tory locusts of Europe, where it sometimes does a great deal of damage. 

 The insect is essentially an inhabitant of the temperate zone, and this 

 would make it appear probable that its permanent breeding-ground lies 

 somewhere in the Nilgiri or other hills, whence it might easily be carried 

 upon the south-west monsoon across the presidency. The presence of 

 nearly full-grown larvae shows that the original flight must have 

 remained in the district sufficiently long to have laid their eggs, and for 

 the eggs to have hatched, and for the larvae ^to have passed through most 

 of the early stages, a process which probably occupied some months. In 

 the Palsearctic zone P, cinerascens is said to lay its eggs in the autumn, 

 the young hatching out in the following summer, but we are as yet en- 

 tirely in the dark as to the habits which the insect acquires when it passes 

 out of a temperate climate into a tropical one. 



Locusts in Assam. 



Assam is not generally troubled by locusts, though in the cold 

 weather of 1890-91 a stray flight of Acriditim peregrinum, from North- 

 Western India penetrated into it. In 1879 also both the autumn and 

 winter crops in Novvgong were reported by the Director of Agriculture 

 to have been largely destroyed by locusts, which were said to have come 

 from the tall grass jungle at the base of the Khasi and Mikir Hills, 

 where they breed permanently. Nothing is known of the identity of this 



P. migr&toriusy and the specimens of the two forms in the Indian Museum (as determined 

 by Dr. Henri de Saussure) seem to point to this being the case. According to the synopsis 

 given on page 119 of Dr. Saussure's Prodromus (Edipodiorum^ in P. cinerascens the 

 male is smaller than the female, the punctation on the pronotuin is somewhat coarse, the 

 notch in the carina is well marked, and the teeth on the posterior femora are large ; while 

 in P. migratorius the male is much the same size as the female, and the punctation on 

 the pronotum, the notch on the carina, and the teeth on the posterior femora are less 

 marked. To these characteristics Mons. Frey Gessner adds that the carina on the thorax 

 of P. cinerascens is elevated into a well-marked ridge, while that of P. migratorius is 

 much less distinct. These characteristics however seem, in the absence of any well-marked 

 geographical boundary between the areas in which the two forms occur, to be of scarcely 

 sufficient importance to justify their sepai'atiou into two species, this being especially the 

 case, as Dr. de Saussure writes that the females of the two forms are often almost indis- 

 tinguishable. 



