38 THE ANATOMY AND DEVELOPMENT OF PERIPATUS NOVAE-BRITANNIAE. 



Breeding-period, Period of Gestation, etc. 



The production of embryos probably takes place all the year round in P. novae- 

 britanniae: — this is also probably the case with the Neotropical Peripatus, and Huttou 

 found that P. novae-zealandiae produces young all the year round. 



P. leuckarti according to Fletcher breeds through about f of the year, the most 

 prolific period being the six months from October to March. As a general rule it 

 does not breed during the winter months (May — August), and in this respect differs 

 markedly from the New Zealand species. 



There is no means of determining the period of gestation except by periodic 

 observations. In P. leuckarti Fletcher estimates it at 6 — 7 months. In P. capensis, 

 as shown by Sedgwick, the period of gestation is 13 months; longer than in any 

 Mammal. The fertilised ova pass into the oviduct in April and the young are born 

 in May of the following year (Sedgwick). The period of incubation observed by Dendy 

 in a deposited egg of P. oviparus was 17 months. That is to say, one of the eggs 

 laid in his vivarium in Melbourne hatched out after an interval of a year and five 

 months. 



In P. novae-britanniae, where the embryos are born in strict succession, only the 

 one nearest the vagina in each uterus being ready for birth at one time, it is possible 

 that the period of gestation for a given embryo is even shorter than in P. leuckarti. 

 It would also appear probable that the extraordinarily long period of gestation in P. 

 capensis is in correlation with the uniformity of the ages of the uterine embryos. 



CLASSIFICATION. 



It is not to be expected that a new species of Peripatus would throw any fresh 

 light on the systematic position of this delightful creature. Nevertheless a few remarks 

 on this subject may not be out of place. Its relationships being obviously divided 

 between the Annelida and the Arthropoda, its place in a separate Class of equal 

 value with either of these groups would seem to be clear enough. Hatschek in his 

 Lehrbuch regards the Onychophora as of equal value with the Arthropoda. The point 

 upon which I wish to say a few words is with regard to the name of the Class to 

 which Peripatus belongs rather than its position in the system. There is an objection 

 to the name Prototracheata (or Protracheata as it was originally written). This was 

 applied to one of Haeckel's theoretical groups, and the name was adopted by Moseley 

 after his discovery of the tracheae. It is a good name and has done good service in 

 embodying a notable conception. The objection to it arises from the fact that there 

 are reasons for supposing that tracheae have had a polyphyletic origin. If the name 

 be accordingly rejected on this account, shall a new name be invented or shall an old 

 name be re-established ? Assuming that the latter course be adopted, which old name 

 should be revived, Malacopoda or Onychophora ? 



In an interesting paper on the classification of the Arthropoda, Kingsley (12) says 

 he prefers to use the name Malacopoda rather than Onychophora because it is older 

 than the latter, having been introduced by Blanchard in 1847. It is certainly the 

 older name, but it was not given by Blanchard but by de Blainville in 1840. This 



