1936] New Thysanoptera from the United States 9 
cies from its congeners. The distinct dorsal reticulation, the 
oblique truncation of the dilated tips of the stout setse, and 
the transverse pronotal thickening are all peculiar to it. It 
bridges beautifully the gap which has previously existed 
between the group comprising Sagenothrips, T erthrothrips , 
Glyptothrips (and possibly one or two other genera) and 
that portion of the Trichothrips group which culminates in 
Malacothrips and Eurythrips. On the basis of the defini- 
tion alone of Sagenothrips it would seem more properly as- 
signable to that genus; but I find little excepting sculpture 
to exclude it from the older genus Eurythrips. Further- 
more, in the series of Eurythrips before me, a complete 
transition is observable in sculpture from those species 
which are nearly glabrous above to such species as the pres- 
ent one, in which the dorsal anastomosing lines take on a 
polygonal disposition and become pronouncedly elevated. 
Differences in sculpture which are of degree rather than 
of kind are seemingly never of generic, and certainly never 
of tribal, value in the Thysanoptera. Our classificatory 
scheme of the group contains many super-generic terms 
which have been proposed as the result of an eager and pre- 
mature search for differences, untempered by an equal assi- 
duity in a search for similarities. 
