222 Alexander Pctniukevltch, 



he fails to mention altogether either the calamistrum or the cri- 

 bellum. In fact he does not mention even the spinnerets. Yet 

 the spinnerets are visible in Titanoeca ingenua v^^hich is by far the 

 better preserved species. The spinnerets are far apart, reminding- 

 of recent Drassids. Xo cribcllum is visible. The legs are extra- 

 ordinarily well preserved and the fourth metatarsi do not show 

 anything like a calamistrum. It is therefore not probable that the 

 spider in question is either a Tiianoeca or any other cribellate 

 species. But while the exclusion of this species from the division 

 of Cribellatae is a comparatively simple matter, it is almost impos- 

 sible to estal)lish its true relationships. On account of its general 

 appearance and the strvicture of the spinnerets I have placed both 

 species provisionally under the family Drassidse. 



Of the forty-seven species of spiders presented in this paper, 

 NcpJiila pennatipes and Tetragnatha tcrtiaria are the only ones 

 whose generic identity seems to be sufficiently well established. 

 The three species of Tlioiiiisits undoubtedly belong to the family 

 Thomisidae, but the genus in its modern conception remains uncer- 

 tain. The same may be said about the species referred to the 

 genus Epeira of the family Argiopidae (Epeiridae). The 

 genera Tctlmcus, Parattiis and several new genera proposed by 

 me all deal with extinct forms and have therefore a different value 

 from genera of recent spiders. None of the remaining spiders 

 can be placed in the system satisfactorily. In these cases I did 

 not feel justified to establish new generic names, a procedure 

 which is advisable only where it is sure that the species does not 

 belong to the genus under which it was originally placed. Each 

 case will be discussed separately. In each such instance the genus 

 used by modern arachnologists for recent species may have only 

 the value of a vague approximation. 



ORDER ARANE^. 



Spiders represent a very natural order and already in the Upper 

 Carboniferous or Pennsylvanic Period are easily distinguishable 

 from all other Arachnida. In all recent spiders with the excep- 

 tion of the family Liphistiidae of the sub-order Alesotheb'i? and in 

 all Tertiary spiders known the abdomen appears unsegmented. 

 In all spiders without a single exception the abdomen is joined to 

 the cephalothorax by means of a very thin petit^lus rei>resenting 



