360 Wisconsin Academy of Sciences^ Arts and Lettirs. ■ 



class of work will be least harsh in their criticism of its 

 defect^;. 



The key is based almost entirely on the generic descrip- 

 tions, and is designed not only to aid in the identification of 

 genera, but also, in a general way, to group together those 

 genera which have common characteristics, and thus to aid 

 in a comparison of the different groups. Its usefulness 

 must be lessened by the fact that the generic position of a 

 species has been commonly determined merely by its pos- 

 sessing a greater number of the characteristics of one genus 

 than of any other. For example: Cyrba Simon has legs 

 4, 1, 3, 2. The greater number of characteristics of C. bi-mac- 

 ulatu Keyserling carry that species to the genus Cyrba, al- 

 though it has the leg-formula 4, 3, 1, 2. If in the key Cyrba 

 has been distinguished from other genera by the fact that its 

 leg-formula is 4, 1, 3, 2, bi-maculata must go elsewhere. 



We have also, for the purpose of facilitating comparison, 

 arranged the characteristics of the different genera in the 

 form of a table. 



We have been perplexed by a lack of precision in the 

 stating of characteristics. We venture to suggest that it 

 would be well to express the dimensions of parts in terms of 

 other parts of the same species. For example, the clypeus 

 should be described not as " very low," or " rather high," but 

 as one fi.fth or one half as wide as the middle anterior 

 eyes. We believe that Menge is the only author who states 

 definitely the height of the cephalothorax. He does so by 

 comparing the height with the width. 



Not having the work in which it is described, we have 

 omitted the genus Portia Karsch. In his Arachnol. Blatter 

 V. Zur Attiden-Gattung Portia, Dr. Karsch says that this 

 genus resembles Eris (C. Koch) Simon, but differs from it in 

 that the first pair of legs is not much more robust than the 

 others; metatarsus -j- tarsus of the fourth are longer than 

 patella + tibia of fourth, not equal or shorter as in Eris) ; and 

 the spines on the tibiae and metatarsi of the hind legs ex- 

 tend to the base. The quadrangle of the eyes, also, is not 

 wider behind than in front. 



As we have undertaken to prepare a monograph of this 



