395 



with only a light fringe of hairs. Legs long. Ovipositor curved 

 backwards. 



In the species of all other Thysanopterous families the joints 

 of the maxillary palpi never number more than three, and of 

 the labial palpi never more than two, and it is on account of 

 the abnormal number of their palpal joints that the iEolothripid 

 genera forming the Nearctic division Orothripinœ are of such 

 interest. In describing the genus Stomatothrips. Mr. Hood 

 makes some interesting generalisations on the probable evolution 

 of the Thysanoptera, but of course, as Hood admits, we require 

 a great deal more material — or evidence — before we can usefully 

 or safely make such generalisations. 



Key to the Gexer.\ of the íEolOthripid.í:. 



1. All antennal joints freely movable^; joints of labial 



palpi fewer than in the maxillary palpi 2 



Three or four terminal antennal joints closely united ; 

 maxillary palpi three-jointed, labial palpi four-jointed 



^olothripinse 6 



2. Maxillary and labial palpi 8-5, 8-3 (or 4), or 7-5 jointed 



respectively. (Genera Nearctic.) Orothripinae -, 



Maxillary and labial palpi 3-2 jointed . . Melanothripinae 5 



3. Palpi 8-5 jointed ; wings expanded apically 



Stomatothrips Hood. 

 Palpi 8-3 (or 4) or 7-5 jointed ; wings not expanded 

 apically 4 



4. Palpi 8-3 or 4 jointed ; forewings with dark longi- 



tudinal bands along posterior margin ; head longer than 



wide Erythrothrips Moulton. 



Palpi 7-5 jointed ; forewings with dark cross bands 



Orothrips Moulton. 



5. Second antennal joint produced apically in the form of 



a tooth Ankothrips Crawford. 



Second antennal joint simple . . . Melanothrips Haliday. 



* I have not seen a specimen of Stomatothrips, which is described as 

 having antennal " segments 7-9, more or less compactlj- united." 



