622 Mr. R. I. Pocock on a 



Machachi and Corazon in Ecuador*. Subsequently Brole- 

 mann f identified it from Guatemala. This author has also 

 described a species with a somewhat similar modification 

 of the anal legs from Venezuela and Brazil, naming it 

 Otostigmus GoeJdii. 



Within the last few years the British Museum has received 

 fresh material of this genus from South America, represented 

 by specimens collected on the Amazons by Messrs. Austen 

 and Cambridge and by other examples from Ecuador. The 

 Amazonian species is probably the same as P. scabricauda. 

 The Ecuador species, two in number, are quite distinct. One 

 of these is probably identical with the species collected on 

 Machachi by Edward Whymper, which 1 erroneously, as it 

 now proves, referred to P. scabricauda, Sauss. The male of 

 one of this Ecuador species, from Riobamba, differs from the 

 male of P. scabricauda in being furnished with very distinct 

 claspers. These take the form of a stout lightly incurved 

 process jutting backwards from the inferior angle of the coxa 

 of each of the legs of the twentieth pair, and reaching to 

 about the middle of the sternal plate of the twenty-first leg- 

 bearing somite. A much smaller tubercular process occupies 

 the same position upon the legs of the nineteenth pair. In 

 the male of the other Ecuadorean species, from Cachavi, the 

 claspers on the legs of the twentieth pair are much stouter 

 and longer, extending backwards to the extremity of the 

 sternal plate of the twenty-first leg-bearing somite (see fig. A). 

 Those on the legs of the nineteenth pair are also relatively 

 larger than in the Machachi and Riobamba specimens, and 

 are short, cylindrical, apically rounded processes. The legs 

 of the preceding pairs are also furnished with coxal tubercles. 

 In the female of the Cachavi species there are coxiil processes 

 on the legs of the twentieth pair as large as those on the 

 nineteenth pair in the male. 



Secondary sexual characters of four distinct kinds are now 

 known in the males of Par otostigmus. Firstly, there are the 

 femoral processes of the anal legs, w'hich I pointed out in 

 1890 and Brolemann in 1902 to be a male feature. _ Secondly, 

 there are the coxal claspers above described. Thirdly, there 

 is the remarkable modification of the last tergal plate, which 

 is produced into a long and stout subcylindrical process in 

 one of the Brazilian species, P. caudatus j. Lastly, there is 

 the modification of the tibial segment of the anal leg in 

 P. tibialis, Brol. 



* Ann. & Mag-. Nat. Hist. (6) vi. p. 142 (1890). 



t M6m. Soc. Zool. Fr. xiii. p. 96 (1900). 



X Brolemann, ' Revista Mus. Paulista,' v. pp. 37 & 39 (1902). 



