20 



NATURAL SCIENCE. 



July, 



compressed at the base, the remaining part being normally slender, 

 though sometimes slightly curved ; but in the fully formed notes the 

 distal part of the bristle is bent at right angles to the basal part, 

 which is enormously expanded and flattened from side to side {see 

 Fig. 2, C and D). Here and there amongst the notes rises a normal 

 bristle, showing that all the hairs, presumably to allow free room for 

 vibration, have not become involved in the formation of the instru- 

 ment. It may also be noticed from the figure that the ends of the 

 hairs are bent in the same direction and keep clear of each other. 

 Their appearance, indeed, reminds one forcibly of a number of 

 weathercocks or streamers before a stiff breeze, or of the heads of a 

 crowd of stork-like birds all gazing in the same direction. When the 

 chelae are waved up and down, the tips of these notes catch against 

 the roughness of the contiguous area on the basal segment of the 

 first leg (Fig. 2, B), and, being thrown by this means into a state of 



Fig. 2. — Stridulating Organ of Indian Scorpion, Scorpio swammerdami . 



A, Coxa of pincer, with key-board x. B, Coxa of first leg, with rasp z. C, Portion 

 of key-board, showing notes. D, one of the notes. E, Diagram of portion of rasp, 

 showing papillae. F, Diagram of papillae in side view. 



vibration, produce the hissing or rustling sound that has been 

 described. The roughness, when examined under an inch objective, 

 appears to consist of a thick cluster of granules, but these when more 

 highly magnified take the form of irregularly arranged, variously sized 

 papillae, shaped somewhat like a human incisor tooth {see Fig. 2, E 

 and F). It should be added that the figures and descriptions here 

 published are taken from an example of the largest-known Indian 

 scorpion, Scorpio swammerdami. Probably the specimen examined 

 by Wood-Mason — " a gigantic one from the Upper Godaveri 

 District " — was also a representative of this species. But this is not 

 certain, nor is it of any special importance, seeing that the organ is 

 found in all the Oriental species of Scorpio ranging from Bombay to 

 Borneo. 



Curiously enough, however, in the species usually referred to the 

 same genus inhabiting tropical Africa an analogous organ exists, 

 which, although agreeing with the one just described in structure and, 

 broadly speaking, in situation, yet differs both in the arrangement of 

 its parts and in exact position, and has evidently originated entirely 

 independently of the other in response to the stimulus of similar 

 needs. Like the organ discovered by Wood-Mason, this new one is 



