824 Prof. T. Thorell on Dr. Bertkaus 



nature of the division of the Spiders into Cribellata and 

 Meromammillata. Even if \fQ do not assign, in general, any 

 great weight in the phylogeny and classification of the Spiders 

 to the form of their webs, it must be admitted that it is at 

 least probable that spiders that fabricate regular or so-called 

 geometrical webs have a common origin and belong to one 

 and the same higher group, or, in other terms, that this 

 industry cannot have arisen spontaneously and independently 

 in two or more different and natural higher groups. What 

 Bertkau has remarked (see above p. 322) as a proof of a 

 close affinity between spiders with and spiders without a 

 cribellum, may, with some modification and with more 

 truth, be adduced as a reason for the affinity between the 

 spiders which make circular webs. Only on the supposition 

 that all spiders have originally constructed such webs, but 

 that most of them have in the course of time lost this talent, 

 could it be admitted that spiders belonging to radically different 

 groups can give their webs such an artistically finished and 

 almost identical form. But for such a supposition there is no 

 reasonable ground. It may be uncertain which of the actual 

 spiders are most nearly related to the original ones — whether 

 it be the Territelarite, or the Tubitelarite, or another group; 

 but that the first spiders were Orbitelarias, nobody will, I be- 

 lieve, think possible. In the case before us, the form of the 

 web appears to me to be of such importance that it can 

 scarcely be overestimated. Moreover, the typical Uloboroida?, 

 i. e. the genus Ulohorus^ has so many structural features in 

 common with the Epeiroida3 and Tetragnathoidaj, that also in 

 this respect there is nothing that militates against the uniting 

 the Uloboroidaj with these families in one and the same tribusi 

 Any one who, without knowing the genus Ulohorus^ gets a 

 specimen of this genus in his hand will, I believe, see that he 

 has before him a spider that is related to Epeira or Tetragnatha. 

 Byptiotes deviates rather strongly both from Ulohorus and 

 from the Epeiroidse, and demonstrates together with Miagram- 

 mojyes and the Dinopoidas, how materially even a natural group 

 of spiders, such as the Orbitelarite, may vary, both in its in- 

 ternal and external characters and in its industry. 



From what I have here said, it will be seen that though I 

 fully acknowledge Dr. Bertkau's merits in having given many 

 most valuable contributions towards a more perfect classifica- 

 tion of the Spiders, I cannot find that he has been successful 

 in his attempt at laying down new principles for this classifica- 

 tion. His chief groups, the Tetrasticta and the Tristicta, as 

 {ilso the Cribellata and the Meromammillata, and even the 

 f'erissonycha and the Artionycha, appear in fact to me to be 

 gather artificial than natural units ; and he has perhaps also. 



