OCR Text |
Show 1902.] STRIDULATING-ORGAN IN A SCORPTON. 223 middle line ; but in many of the southern types-e. g., P. plani-manus, P. neglectus, P. villosus-the whole upper surface of the segments tends to become flattened ami horizontal both in a longitudinal and transverse direction. A similar granular field is developed between the dorsal keels on the last abdominal tergite. Text-fig. 26. B Stridulating-organ of Parabuthus flavidus. A Lateral view of tail, to show the action of the sting during stridulation. B. Dorsal view of last somite of abdomen and of 1st and 2nd caudal segments, showing the ridges on the median groove of the two segments. If the tail of one of these Scorpions be brought into the attitude usually assumed by these animals when striking, and the point of the sting be scraped over the granular field, a very distinct sound is emitted, resembling that produced by chawing the point of a needle over fine sand-paper \ There is as yet no direct evidence, based on observation of the living animal, to prove beyond dispute that these granules have the function here assigned to them, but the facts which support the conclusion are the following :- (1) The sound can be artificially produced, and is audible to me at a distance of ten yards or more. (2) The scorpion itself is capable of performing all the movements necessary for its production. 1 A similar but less complete development of granules, subserving no doubt the same purpose, is observable in two North-African species of Buthus-B. bicolor and B. ceneas. |