Tertiary Spiders and Opilionids. 251 



The separation into sub-families is based chiefly on the struc- 

 ture of the palpi in both sexes and the separation into genera on 

 characters the majority of which are not easily ascertainable even 

 in recent forms, especially in the case of females. Most of the 

 recent spiders belonging to the sub-family Erigoninse are minute, 

 those of the sub-family Linyphiinse larger and often resembling 

 Theridiids with which they were originally classified, but from 

 which they are easily separable by the structure of their fourth 

 tarsi and chelicerse. 



Genus Linyphia Latreille. 



Scudder has placed a single species under this genus. I have 

 placed under it Scudder's Theridiiim scclusinn which is certainly 

 not a Theridiid and two new species. All these species have the 

 general appearance of recent Linyphias, but it is impossible to say 

 whether they actually belong to this genus. 



Linyphia seclusa (Scudder). 



= Theridiiim seclnsuin Scudder, Tertiary Insects, 1890, p. 74, 



Plate II, fig. 20 ((5). 



Scudder described three specimens, but one of these is a dis- 

 tinctly dififerent species and has been placed by me under the genus 

 Palccopachygnatha. This leaves two specimens of which No. 7816 

 I have not seen. The figure and description given by Scudder 

 referr to specimen No. 9026 (now 88) of the Collection of the 

 Museum of Comparative Zoology of Harvard University, which 

 I have carefully examined. 



It is a well preserved male. The description given by Scudder 

 is correct. It must be added that the fourth tarsi are well pre- 

 served and show no trace of a comb. There are distinct spines 

 of the Linyphiid type on all joints except tarsi. 



Linyphia retensa Scudder. 

 Scudder, Tertiary Insects, p. 75, Plate 11, figs. 25, 27 (S ). 



A single male and its reverse have been described by Scudder 

 under the Nos. 12976, 13212 and 14032. Of these I have seen 

 only No. 12976 (now No. 89) of the Scudder Collection of the 

 Museum of Comparative Zoology of Harvard University. The 



