2i6 Alexander PctniitkcvltcJi, 



When it comes however to a comparison Ijetween American and 

 European spiders extreme caution is necessary. With famihes 

 and genera uncertain, what reliance can be placed upon deductions 

 made from such a comparison? Scudder may be pardoned for 

 his attempt to do it, but no excuse would be valid in the case of a 

 man thoroughly versed in the modern systematics of recent 

 spiders. Faunistic and climatic conjectures are therefore entirely 

 out of place. 



Another side of the investigation was also sadly disappointing 

 to the author, namely the complete absence of any structures which 

 would allow one to unravel the mystery of the origin of the method 

 of reproduction peculiar to spiders. In those cases where the male 

 palpi are well preserved they show that at that geological period 

 the copulatory apparatus was already fully developed and occupied 

 the same position as in recent spiders. In one case the epigynum 

 of a female is also surprisingly well preserved and quite of the 

 type found in recent species. 



THE RELATIONSHIPS OF ARACHNIDA. 



It may Ijc not quite out of place here to consider first of all the 

 relationships of Arachnida and their place in the System of 

 Arthropoda. Already in my monograph of Palaeozoic Arachnida 

 I have pointed out the reasons why Pycnogonida, Tardigrada and 

 Pentastomida ( Linguatulida) have no place among the Arachnida. 

 On the other hand I have included under Arachnida the Gigantos- 

 traca and the Xiphosura (Limuloids). I have also given a defi- 

 nition of the Class Arachnida in conformity with our knowledge 

 at that time. Since then I have done some extensive study of 

 segmentation in Arthropods, part of which studies is in press at 

 this moment. The readers interested in the subject are referred 

 to this paper which will appear in the Journal of Morphologv. 

 But the results of the investigation may be briefly summarized as 

 follows : The Lankesterian division of the body of an Arachnid 

 into a prosoma, mesosoma and metasoma of six segments each is 

 entirely untenable and must be dropped. The Xiphosura have 

 much in common with the Arachnida, Init also possess many fea- 

 tures which make their relationship with the Arachnida more than 

 doubtful. Their arterial circulatory system is perineural. Their 



