92 MKKI-TIC VARIATION. [PART i. 



inoi, o\, T, in some of the species the number appears to be 'very 

 con-taut tin- tin- -peejes, in the case of others, great individual 

 \ai iation i- -een to oerur. SEDOWICK*8 observations in the caseof 

 /' 1,1,1;! /-'1 1 1 -he\\ conclusively that these variations cannot be 

 a- ribed t,. difference in age. There is besides no ground for sup- 

 po-ing that iii'Tease in the number of legs occurs in any species 

 after birth, and it i>- in fact practically certain that this is not the 

 case. In Pi'n'jHitus cupensis, which was exhaustively studied by 

 S. cl_-\\ i.-k, the appendages arise- in the embryo successively from 

 before backwards the most posterior being the last to appear, and 

 til-- full nu i niter is reached when the embryo arrives at Sedgwick's 

 Stage (I. The following is taken from the list constructed by 

 S.-dgui''k t'r>m all sources, including his own observations. As 

 tin- bibliography given by him is complete and easily accessible 

 it is not repeated here, and the reader is referred to Sedgwick's 

 monograph for reference to the original authorities. 



SI;IM;WICK, A., Qiutrt. Jour. Micr. Sci. XXVIIL, 1888, pp. 431- 

 4!i:i. Plates. 



i A Kim AN SPECIES. 



/'. capensis: 17 pairs of claw-bearing ambulatory legs (Table 

 Mountain. S. Africa ). 



/'. l>nl t',,11,-1 : is pairs of legs, of which the last pair is rudiment- 

 ary (Table Mountain. S. Africa i. 



Sei|g\vi,-k ha- \ainined more than 1000 specimens from the 

 ('ape. and ha- only seen one specimen with more than 1<S pairs of 

 leg-. This individual had ^0 pairs, the last pair being rudiment- 

 ary. It closely resembled I', tin f /'mi ri , but differed in the number 

 of lc'4-> and in certain other details (q. v.); Sedgwick regarded this 

 form provisionally as a \ariety of P. Imlfmiri. 



I', mosleyi: '2\ and :>:> pairs of legs : near AVilliamstown, S. 

 Africa. The specimens with '2'2 legs w-re two in number and were 

 both females. They differed in certain other particulars from the 

 form with i^l le->. but on the whole Sedgwick regards them as a 

 Variety ..I' t he- >ame species. 



/'. brevis i I>K ULAINVII. 1,1:1: 14 jiairs of legs. (This species not 



II b\ Sedgwick.) 



()thei- species In-m S. Africa which have been less fully studied 

 are stat.-d to ha\e lit, ^1 ;m ,l -2-2 pairs ..f legs respectively." 



In all South African forms, irrespective of the number of legs, 

 'he generative opening is subterminal and is placed behind the 

 la-t pair of fully developed legs (between the l.sth or rudimentary 

 pair iii /'. l>nt/nin i). SI-.I.CWICK. jp. 440 and 4.~>1. 



ArsruAi.. \SIAN Sn:cii:s. 



P. novcB-tealandias, 1"> pairs of legs. New Zealand. 

 P. leuckartii, \"> \>-.i\r <>\' legs. (Queensland. 



Ill both o| these speeles tile geliel-ative opening IS between tile 



last pair of leg-. < SKIXJWICK. p. 4sc. i 



