60 TERTIARY INSECTS OF NORTH AMERICA. 



legs, 7.15""° ; its femora, 2.6°"" ; its tibia (proper), 0.8™" ; (true) first joint 

 of tarsi, 2"""; second joint, 1°""; third joint, 0.7.5°""; femora of fourth pair 

 of legs, 3™" ; its tibia (proper), 1""° ; combined tibia and first joint of tarsi 

 (as preserved), 3.5°"°. 



This species is very readily separated from the others by its size, and 

 undoubtedly belongs to a genus distinct from them; the specialization of 

 the tibia proper is sufficient indication of this. 



Florissant. One S, No. 4742. 



Suborder TUBITELARI^ Thorell. 



This group of spiders, given to the construction of silken tubes above 

 ground, is considered by Thorell as the most lowly organized of the Ara- 

 neides, and it is interesting to find that it is far better represented in the 

 Tertiary deposits than any other, comprising more than one-third of the 

 species now known and 36 per cent, of the fossil species of Europe. It is 

 equally remarkable for its diversity of form, all the families which are rich 

 in genera in Europe at the present time being well represented in the Ter- 

 tiaries of that country, and particularly in amber, both in genera and spe- 

 cies; especially, as we shall see below, is this true of the Drassides, a group 

 wliich is only surpassed in the number of its fossil species and the variety 

 of its genera by the Theridides. It .is, however, neither of these families, 

 but the Epeirides, which predominates in the American Tertiaries, though 

 next to these the Tubitelarise stand pre-eminent, and particularly the family 

 of Drassides, already mentioned. The same three families, viz, Dysderides, 

 Drassides, and Agelenides, which are best represented in the European 

 Tertiaries and are most abundant in species at the present day, are also 

 present in the American strata, the first by a single species, the second by 

 five, and the last by two, in all one-fourth of the American Araneides. 

 (November, 1881.) 



Family DYSDERIDES Koch. 



Three genera of this family, Dysdera (four species), Segestria (eight 

 species), and Therea (two species), have been found in Prussian amber, 

 and comprise all the fossil species known up to the present time. To this 

 list we can add from America one species, belonging to the genus most 

 richly represented in amber. So far as known the living species of this 



