310 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 112 



fig. lc and Thraupis virens episcopus, fig. le) have fairly large 

 mandibles, but none possess the serrated inner surfaces. 



In Trochiloecetes the mandibles are without visible condyles. The 

 anterior portion, at the angle of the "L," is fused with a small pro- 

 jection on the inner side of the marginal carina, just in front of the 

 palpi. The long, posterior tip seems to be without support; it moves 

 transversely along a short band projecting from the premarginal nodus, 

 but it probably has a muscular attachment to the band, a condition 

 that would allow a forward and backward movement of the pointed, 

 anterior portion of the "L." 



In species of Ricinus (auct.) the mandibular condyles differ 

 greatly in the amount of their development. Those from Phlegopsis 

 have well developed articulations (see fig. lc), especially of the 

 anterior condyle, while those from Dysthamnus (typical of the small 

 mandible type) have the articulation rudimentary, but nevertheless 

 present. 



In all the species of Trochiloecetes that I have examined there is a great 

 similarity in the shape and situation of the mandibles, as may be 

 seen from the figures of the species described on succeeding pages. 



Although Clay asserts that the tip of the left mandible is bipartite, 

 I have not been able to confirm this statement. It is true that the 

 tip of the left mandible in Ricinus (auct.) is bipartite, but apparently 

 it is not in Trochiloecetes. 



Clay states further: "There are three closely associated stylet- 

 like structures, almost certainly of hypopharyngeal origin, which are 

 joined by a common membrane, only the distal ends being free." 

 Actually, the median stylet is the sucking tube, while the two lateral 

 ones form the sheath that supports and shields it. This structure is 

 not always clearly visible, but in some specimens all details are clearly 

 defined. There is considerable variation in the details of these struc- 

 tures, but generally speaking the same pattern is found throughout 

 the genus. 



Clay mentions the outgrowths from the dorsal wall of the preoral 

 cavity as forming a groove to hold and guide the hypopharyngeal 

 apparatus, but this is slightly misleading. These outgrowths are the 

 anchorages to which are fused the sides of the collarlike structure, 

 and it is through this structure that the hypopharyngeal apparatus 

 is protruded and retracted. Clay also states: "The mandibles are 

 lightly sclerotized and the piercing blades lie parallel to the median 

 structure." The long, posterior portion of the mandibles does lie 

 parallel to the sucking apparatus, but the actual piercing blades are 

 at the anterior end, pointing inward, at right angles to the median 

 structure. The mandibles are L-shaped, the long arm pointing back- 

 ward and the short, piercing blade pointing inward. 



