THE ANATOMY AND DEVELOPMENT OF PERIPATUS NOVAE-BRITANNIAE. 5 



species was published (25). They are to be distinguished externally from the females 

 by their less numerous appendages. To judge from the material at my disposal which, 

 including the older embryos taken from the females, amounted to at least 20 specimens, 

 the rule seems to be for the female to have 24 pairs of claw-bearing appendages 

 and the male 22 pairs. But one of my adult males has 23 pairs of claw-bearing 

 appendages (V) 1 . 



The females attain larger dimensions than the males, ranging in length from 

 14 7-"> mm. (X) to 5475 mm. (II) and in width of body from about 2 to 5 mm. Two 

 of the males (XII and XIII) were of almost equal size, namely 15 mm. long and 2 mm, 

 wide — the third male (V) was considerably larger, attaining a length of 26 mm. with a 

 width of about 3 mm. 



The predominance of the female over the male appears to obtain with all species 

 of Peripatus. In P. leuckarti (New South Wales) Mr Steel (23) found that out of 

 579 specimens collected by him in one season, 390 were female and 189 male or 07 

 per cent, female and 33 per cent, male; and the females were, on the average, one-third 

 to one-half longer than the males. 



For the present, I regard the male of P. novae-britanniae which had 23 pairs 

 of legs (No. Y | as an exception rather than as a frequent variety, because I have 

 taken advanced embryos from the uterus with their full complement of claw-bearing 

 appendages, viz. 22 pairs (I have four such embryos), while less advanced embryos 

 from the same female were found to have 24 pairs of claw-bearing appendages. Thus 

 in specimen No. II the two embryos which lav nearest to the vagina had 22 pairs 

 of legs; while the two younger embryos following upon the first two, had 24 pairs 

 of legs. I cut sections through one of the former and one of the latter, and as I 

 had expected they turned out to be male and female respectively. 



In the Neotropical species of Peripatus the females tend throughout to have a 

 larger number of legs than the males, but the numbers vary considerably within the 

 limits of a given species. Thus in P. jamaicensis Grabham and Cockerell, the number 

 of claw-bearing appendages is said to vary from 29 to 43 pairs, so that some of the 

 males would have a greater number of appendages than some of the females. [Pocock 

 (16) and Cockerell, Notes on Peripatus jamaicensis, Zool. Ang. 1894, p. 341.] 



Sedgwick established the fact that in Peripatus the young are born with the full 

 number of legs, none being added after birth. Indeed in the South African species 

 there seems to be a tendency to reduce rather than add to the appendages, in so 

 far that the rudimentary appendages between which the generative orifice lies, which 

 have been called the anal papillae, are stated in Balfour's posthumous memoir (2) to 

 be "most marked in small, and least so in large specimens." 



In the position of the generative aperture behind the last pair of legs our species 

 superficially resembles the Cape Peripatus more than any other. In the female the 

 aperture is surrounded by tumid lips. Its position in the male is highly distinctive 

 for the species, being placed at the tip of a relatively long backwardly-directed conical 

 papilla [Fig. 10 a and b]. The last-named structure, i.e. the penial papilla, is the 

 unfailing external sign of the male in P. novae-britanniae. 



1 Eoman numerals in brackets merely refer to particular specimens. 



