8 



EXTERNAL ANATOMY. 



The following studies were made on Cr ambus laqueatellus 

 with occasional references to the other species. The head 

 (Plate A, figs. 1 and 2) is of moderate size, and connected 

 with the thorax by a small neck. The compound eyes (Plate 

 A, figs. 1-4, e) are large and hemispherical, varying some- 

 what in outline in the different species. The ocelli (Plate A, 

 figs. 1-3, o) , situated behind and near the base of the antennas, 

 are present in most of these insects. The antennae (Plate B, 

 figs. 15-17) have from fifty to fifty-five segments in C. laque- 

 atellus, the basal segment being much larger than the others ; 

 the first two are covered with scales and the others with two 

 scale clusters each, on the upper side, while fine hairs are 

 scattered over the remaining surface (Plate A, fig. 9, and 

 Plate B, figs. 15-17). All except a few of the basal joints 

 have several sense pits on each side (generally four in the 

 male and three in the female) . These sense pits are circular 

 in outline, guarded by a row of hairs which arise obliquely 

 from the edge, and are located somewhat irregularly on the 

 joints. Under a high magnifying power the antennal seg- 

 ments appear to have a reticulated surface (Plate A, fig. 10). 



The epicranium is separated from the clypeus by a well- 

 marked transverse suture just in front of the base of the 

 antennae. The clypeus is large and convex (Plate A, fig. 

 3) ; in some species it is more or less swollen in the middle, 

 while in others it is produced in the form of a cone. The 

 cheeks occupy the lower and lateral portions of the face. 

 The small, somewhat triangular labrurn is in front of the 

 clypeus and over the base of the tongue. The mandibles 

 are rudimentary, and armed with bristles which extend in- 

 ward and rest on the base of the tongue. The maxillae are 

 developed into a sucking tube, which is called the proboscis 

 or tongue. This organ varies in length, to some extent, in 

 the different species, and is covered with scales at the basal 

 part. When not in use it is coiled up, like a watch-spring, 

 between the labial palpi, and concealed by them. The labial 

 palpi have three segments, extended horizontally forward 

 and thickly covered with scales. They vary greatly in 

 length in the different species (Plate A, figs. 1, 2 and 3; 



