g6 Annals Entomological Society of America [Vol. III.. 



]jresent additional setae or punctures, mostly in the neigh- 

 borhood of setae i and ii. (One pair of punctures is shown in 

 the figure).* 



Lying abo\-e the mouth and separating the cpicrania is a 

 triangular sclerite, the front. It has two setic near its lower outer 

 angles, and usually between them a pair of ]:>unctures. In 

 Hepialus, however, the setae lie between the punctures. The 

 front and the epicrania are separated by a pair of narrow adfrontal 

 sclerites. each of which has two setae and a puncture between 



them.t 



Bordering the lower side of the front is the clypeus. with a 

 ]jair of setae at each end; and hanging from that, the mo\-able 

 labrum, which belongs functionally to the mouth. Its structure 

 will be mentioned with that of the mouthparts. 



On each side, i)etween the two aiticulations of the mandible 

 is the antenna. (Fig. 29.) It is four-jointed, but all but the 

 second of these are minute. There is a large membranous cone 

 at the base, which Scudder treats as a true joint. It is inverted 

 when the antenna is retracted, and would seem to be no different 

 from the membrane which separates all the joints of the antenna. 

 The antenna is suri)risingly constant in its structure, the arrange- 

 ment of seta: shown in the figure occurs with little change in all 

 the caterpillars studied. The Lasiocampidae alone have a few 

 secondary' seta\ 



The mouth parts are the labrum, or upper lip (Fig. 12), the 

 two mandibles (Fig. 28), and the lower lip (Fig. 2), which in 

 caterpillars is formed of the maxillae as well as the labium. The 

 labrum is oblong, wider than high, with the free edge rounded, and 

 with a notch, through which the food is guided into the mouth. 

 It bears (i) a row of four setce across the top of the notch (i and ii) , 

 (2) two pair of seta; on the lateral edge (iii and iv), (3) two pair 

 of setae on the tip of its two lobes (\' and \i) . There are several 

 punctures, the most noticeable of which is the one indicated in the 

 drawing and marked ia. On the inner side there are a large 

 number of sensory cones, and near the outer edge three larger 

 similar cones. The latter are indicated in outline on the figure. 

 The labrum has been especially useful in furnishing characters. 



t The front, a.s the term used in this article, has been usually called the clypeus, the adfrontals 

 being known as paracylpeals, and the clypevis as antcclypeus or epistonia. I believe that the set 

 of names used here afrrees better with their homologies in other orders. 



* Dyar's mimbcring of the setae, which has been copied in Fi^. 1, is published in Journ. of the 

 N. Y. Entomological Society IV. H'i, with a figure. 



