2 INTEODUOTION. 



to show that the embryos remain thirteen months in the 

 uterus ; that the fertilised ova pass into the uterus in April, 

 and the young are born, fully developed, in the May of the 

 year following. That is to say, the young ova pass into the 

 uterus one month before the young of the previous year are 

 born. I was not prepared for this, and I did not, in 1884, 

 examine my specimens for the early stages until May, when 

 the young were being born. The result was that I missed the 

 early stages of development, and had it not been for the kind- 

 ness of Mr. Walter Heape, who went to South Africa last 

 summer, and who collected and brought back some more live 

 specimens, I should have been obliged to leave the early stages 

 undescribed. Thanks to him, however, and to my experience 

 gained in the previous year, I was able, in 1885, to find several 

 of the younger stages, and to complete my observations. 



Two species ofPeripatus are commonly found at the Cape. 

 One, the most common, is the well-known Capensis; the 

 other is a new species, differing from Capensis in having 

 eighteen pairs of fully-developed legs, in being of a smaller 

 size, and in other points. This species I propose to call Peri- 

 patus Balfouri. It will be fully described in the forth- 

 coming monograph by Moseley and myself on the ' Species of 

 Peripatus.' 



Besides the work of Balfour and Moseley on the develop- 

 ment of Peripatus capensis, some observations on the 

 development of a West Indian species have been published by 

 Dr. J. Kennel, of Wiirzburg.^ The early stages, to which Dr. 

 Kennel's observations mainly relate, are obviously extremely 

 difficult to follow in the West Indian species, and I do not 

 think that his account of them in the paper above referred to 

 can be regarded as entirely satisfactory. There can be no 

 doubt, however, that the early stages in the development of 

 the West Indian species differ from those of the Cape species ; 

 for instance, there do not appear to be any structures in the 

 Cape species which correspond to the amnion and placenta 

 described by Dr. Kennel. 



' Semper's ' Arbeiten,' Heft ii, Bd. 7. 



