TWO NEW SPECIES OF ONYOHOPHOIfA 401 



possessing only tweiity-tliree pairs. As a rule^ tlie male of 

 the species Horsti has only twenty- three pairs of legs, while 

 the female has at least twenty-four, and as often as not it has 

 twenty-five pairs. The net result of the above facts is that 

 the male has fewer legs than the female by at least one pair. 

 Another fact brought out by this small collection is the vari- 

 ability in number of legs possessed by both male and female 

 ■ — -a feature which is more characteristic of the Peripatinse 

 than of any other snb-family. 



Antennas: — The antenna) taper gradually as far as the 

 thirty-fourth or thirtj^-fifth ring, bnt from that position on- 

 wards they increase in circumference so as to become club- 

 shaped. All the rings, as far as the position above men- 

 tioned, have the same thickness ; but a considerable number 

 of the last fifteen rings may l^o either thicker or thinner than 

 the rest. The presence of the thin ones makes it almost im- 

 possible to count the number of rings which constitute the 

 antenna?, which are scarcely ever fully extended. On this 

 account the number that can be counted varies between forty- 

 six and fifty, or perhaps in some instances fifty-one. 



The Jaws: — The jaws are different from those of any 

 species that has been so far described. The outer blade has 

 two denticles on the inner side of the main tooth. As a rule, 

 111 the genera Peripatus and Peripatopsis there is only 

 one denticle ; while in Paraperipatus and Peripatoides 

 there are none in this position. Similarly the inner blade has 

 two denticles on the inner side of the main tooth, which are 

 followed by a diastema, on the inner side oF which is found a 

 row of smallei- denticles — nine or ten in number. There 

 seems to be no essential difference between the jaws of the 

 two species Weldoni and Horsti. Two vestigial denticles, 

 however, were noticed at the inner moiety of the diastema of 

 the i nner blade in one specimen of the species Horsti 

 (fig. 12a). They are not constant, for the inner blade of the 

 other jaw of the same specimen did not possess them. 

 Nevertheless, they are interesting in that they point to 

 the series being at one time continnous, much as it is at 



