onychophora of west australia. 373 



The Mandibles. 



The cliaracter of these structures has been used very con- 

 si(lera,bly in systematic works, and consequently they have more 

 than a little interest for us here. 



Each mandible consists as usual of two blades. The outer 

 blade presents a single large projection, but no small teeth. 

 Tlie inner blade is provided with a, large principal tooth and a. 

 number of suialler accessory teeth. According to Spencer (12) 

 there are four clearly marked and one minute accessory tooth, 

 whilst Bouvier remarks that, as in P. suteri, P. novce zealandicB, 

 and /-". occidentalis, there are five accessory teeth. In the course 

 of this present research the mandibles have been removed from a 

 large number of specimens, and examined, with the result that 

 whilst one can say that five accessoiy teeth are most common 

 upon the inner blade, there may be six or even seven. In the 

 latter case the extra teeth are very small. There is again no 

 difference to be noted between the northern variety and the 

 southern form previously known as F. occidentalis. There is never 

 an accessory denticle at the base of the large tooth on the outer 

 jaAV blade. 



External Sexual Differences and Crural Papillje. 



There is no difference in the number of legs borne by the two 

 sexes as in Perijxitus nova'.-hritannice, although the two sexes are 

 to be distinguished by other chai'acters associated with these 

 appendages, i. e., the crural pa.pilke. The female a,perture is 

 larger than the male apertuie, as noted bj;- Bouvier, and both 

 apertures are found between the bases of the legs of the l^st pair. 

 Beiiiud the aperture of the reproductive organ in the male, and 

 consequently just posterior to the last pair of appendages, are 

 two sma.ll openings which can be recognised by their slightly 

 tumid, pigmentless lips. These are the apertures of the anal 

 glands. 



The Crural Papilla' are the most distinctive features of tlie 

 male. Unfortunately there has been some confusion as to the 

 number present, and these structures have been taken as of 

 considerable systematic importance. Bouvier (3) gives the 

 follovi'ing table for three males in his collection (the species 

 formerly known as P. wood/wardi or P. gilesii) : — 



Less 1. 2. 3. 4 5. 6. 7. 8. 9. 10.11.12.13.14.15.16. 



r 1110011111000000 



Sp.t.-^ 



(.0110011111100000 



Rt. 



Lft. 



25* 



