i8 NATURAL SCIENCE. July. 



he found the organ and foretold its function before he was aware of 

 the abihty of scorpions to emit special sounds of any kind. An 

 opportunity of verifying this prediction first presented itself at Bombay, 

 when he was on his home journey from Calcutta. Here he procured 

 two black scorpions, and, placing them face to face on a small metal 

 table, goaded them into fury, whereupon they immediately began to 

 beat the air with their great pincers and simultaneously to emit sounds, 

 which were distinctly audible to the bystanders, and "resembled the 

 noise produced by continuously scraping a piece of silk-woven fabric, or, 

 better still, a stiff tooth-brush, with one's finger nails." In another place 

 the sound is said to be " almost as loud as, and very closely similar 

 to, that made by briskly and continuously drawing the tip of the index 

 finger backwards and forwards in a direction transverse to its coarse 

 edges over the ends of the teeth of a very fine-toothed comb," And, 

 finally, in describing the situation and structure of the organ which 

 produces the sound, Wood-Mason says : " The apparatus is situated 

 — the scraper upon the flat outer face of the basal joint [segment] 

 of the palp-fingers ; the rasp on the equally flat and produced 

 inner face of the corresponding joint of the first pair of legs. On 

 separating these appendages from one another a slightly raised 

 and well-defined large oval area of lighter coloration than the sur- 

 rounding chitine is to be seen at the very base of the basal joint of 

 each ; these areas constitute respectively the scraper and the rasp. The 

 former is tolerably thickly, but regularly, beset with stout conical 

 sharp spinules, curved like a tiger's canine, only more towards the 

 points, some of which terminate in a long limp hair ; the latter 

 crowdedly studded with minute tubercles, shaped like the tops of 

 mushrooms." 



It is a pity that this brief preliminary account was never followed 

 by a more detailed and illustrated description of the organ in question 

 at the hands of its original discoverer. But since death has now 

 unhappily rendered this an impossibility, it is undesirable that there 

 should be any further delay in figuring this remarkable instrument, 

 and in publishing a short explanation of certain points in its structure 

 which do not appear in the account cited above. In the first place, 

 however, for the sake of those readers of Natural Science who are 

 not familiar with the details of a scorpion's anatomy, it is proposed to 

 add a few lines on this subject so as to make clear to all the 

 mechanism and structure both of Wood-Mason's organ and of two 

 others that have recently been discovered in some African species, 

 but hitherto neither figured nor described. 



Attached to the cephalothorax, or forepart, of a scorpion's body, 

 are six pairs of appendages, four of which on each side are set apart 

 for locomotion, and constitute the legs properly so called. The basal 

 segments or coxae of these legs are welded together and closely in 

 contact, so as to be capable of but little movement. But immediately 

 in front of the first leg there is a large and powerful limb variously 



