June, '15] BORDEX: MOUTHPARTS OF THE THYSAXOPTERA 



355 



Gottingen an account of the mouthparts. Then follows the account 

 in Uzel's Monograph (1895) in which Uzel adopts Garman's views as 

 to the structure, excepting that he differs with Garman in regard to the 

 mandibles, Uzel holding that the lobes of the maxillae are the mandibles 

 and calling the mandible of Garman the epipharynx. Garman again 

 presented his theory, in the American Naturalist (1896), and offered 

 a strong argument to support his views. In 1899, Pietro Buff a, an 

 Italian, described the structure of Heliothrips hcemorrhoidalis, giving 

 a fairly accurate description, although his illustrations are confusing. 

 Finally, in 1902, W. E. Hinds gave a very good description of the 

 structure of the mouthparts of Anaphothrips striatus, but his figure 

 is at most only diagrammatic. YQvy little comparative work had been 

 attempted before the work of Hinds. 



The presenit work is based on studies made of representatives of all 

 three families of the Thj^sanoptera, including twelve of the genera and 

 some twenty odd species. The material was all collected in the Santa 

 Clara Valley, California. The method employed in collecting and 

 preparing was as follows: The thrips were collected and killed by 

 dropping them directly into 70 or 80 per cent alcohol; dehydrated by 

 passing them successively through 90, 95 and absolute alcohol, then 

 cleared in xylol and mounted in balsam. As soon as mounted, the 

 mouthparts may be separated out by carefully pressing and moving 

 the cover slip with a needle, under the low power of the compound 

 microscope, until it can be seen that the parts are sufficiently separated. 

 In some cases the specimens were cleared by boiling in KOH a few 

 seconds before mounting. 



The work and preparation of this paper were carried on in the Ento- 

 mological Laboratory of Stanford University'. 



The Mouthparts 



The mouthparts of the thrips appear as a broad unjointed cone 

 attached to the extreme posterior edge of the under side of the head and 

 carried so far back that it lies largely under the pronotumwhen at rest. 

 The apex of the cone is usually quite sharp, as in many of the Phloeo- 

 thripidse, in which case the separate parts are longer and more tapering 

 than where the tip of the cone is more blunt, as in many of the Thripidse. 

 The shape of the cone is not of. the same type throughout any one 

 large group or even for the different families, but varies greatly even 

 for the different genera in the same family. 



In the suborder Terebrantia, the mouthparts are connected to the 

 frons by a strongly chitinized thickening rounding the head (PI. 16, figs. 

 1, e and 2, e) which is more or less oblique on the front of the head. In 

 this suborder there is also a strongly chitinized thickening extending 



