58 Mr. E. I. Pocock on a neio 



Apart from the legs, which are almost immovably welded 

 hj their basal segments to the sternal surface of the body, 

 the chelicera3, chelse, and tail are, with one exception, the 

 only organs in a scorpion susceptible of vigorous and rapid 

 movement. The one exception is the pectines. It is in 

 connexion with these appendages that the stridulating-organ 

 now to be described has been discovered *. 



In the course of a recent study of Burchell's manuscript 

 ' Note-book of Brazilian Insects &c.,' Professor Poulton found 

 the following record under the date December 3rd, 1828 : — 



" 1274. Scorpio of a light redish [thus] brown. Legs and 

 claws pale. Several of these were cauglit in my house. I 

 found one feeding on a large blatta which it held close to its 

 mouth with its claws. ' Lacrdia.^ Makes a noise between 

 a hiss and a whistle, v. J. ol. 12. 28, with its pectiniform 

 appendages." 



The word " Lacrdia " evidently represents the native 

 name of the species. Burchell always made a point of ob- 

 taining such names whenever possible, and took the greatest 

 pains in writing them clearly and inserting accents. The 

 reference " v. J. 31. 12. 28 " apparently alludes to a Brazilian 

 journal which has unfortunately not been found. It certainly 

 did not reach either Oxford or Kew. 



At once appreciating the interest and importance of the 

 last sentence of the note. Prof. Poulton arranged for the 

 collection to be searched for a scorpion bearing the number 

 1274. The specimen was soon found by Mr. W. Holland, 

 and Prof. Poulton brought it to the Natural History Museum 

 and asked me to determine it and to examine the pectines, to 

 discover if possible the nature and situation of the stridulating- 

 organ. This I undertook with the greatest pleasure, and with 

 the result that the accuracy of Burchell's observation was 

 substantiated to the full. 



The specimen is a male and belongs to the Brazilian species 

 that I described last year as Rhopalurus Borellii. Although 

 dried, it is sufficiently well preserved to preclude all likelihood 

 of error on this point ; but without the relaxation or removal 

 of the pectines the structure of the stridulating-organ could 

 not be investigated. The examination necessary for this 



* Reference may here be made to the suggestion of Laudois (' Tierr- 

 stimmen,' pp. 22-23, 1874), that the pectines might be capable of emitting 

 sounds by friction. This idea, however, was not supported by facts, and, 

 except that the guess has now been verified, it is on a par with Wood- 

 Mason's view that the prehensile teeth on the digits of the chelse in 

 Buthidse might also be used for this purpose (Proc. Eut. Soc. London, 

 1877, p. xix). 



