1900] ENTOMOLOGICAL NEWS. 315 



(Fig-4, md.) are long and serrate on their inner edges, so as 

 to be effective lacerating instruments. The maxilla? (Fig. 

 4, mx.) are elongate and blade-like and have four- segmented 

 palpi. The labium (Fig. 4, U.) is, though somewhat elongated, 

 truly tip-like and has its terminal lobes not coalesced and with- 

 out pseudo-trache*. The hypopharynx is not short and tongue- 

 like, as in the orthopterous mouth, but is long and slender, and 

 stylet-like. Altogether the difference between the mouth parts 

 of Blepharocera and the racial biting type is one of modifica- 

 tion, and of modification not sufficient to obscure the homolo- 

 gies, although a modification more profound than that shown 

 by the most generalized Lepidoptera or Hymenoptera. On 

 the other hand, there is not much dfticulty in tracing the de- 

 velopment of the Dipterous mouth from the generalized condi- 

 tion of Blepharocera (or SimuUum, or Dixa et al.) to that extraor- 

 dinary specialized condition shown by Musca, where the man- 

 dibles and maxilla? are lost and the labium is so modified that 

 it has no longer any likeness to the " lower lips " of the or- 

 thopterous mouth. 



The other specially interesting point in the imaginal anat- 

 omy of Blepharocera is the structural condition of the com- 

 pound eyes. It has long been observed that seveml flies 

 (SimuUum, Tabanaset a?.) and certain other insects (Libellulidae, 

 Ascalaphus, Ephemeridae, et al.) have two sizes of facets in 

 each compound eye ; that some have the field containing these 

 differently sized facets well delimited, the fields being in some 

 cases actually separated from each other by a non- facetted 

 line or by a constriction. When this constriction is so com- 

 plete that the eye is truly divided we may fairly say that there 

 are two pairs of compound eyes, the two eyes of each lateral 

 pair differing in the size of the facets. This last extreme con- 

 dition exists in the case of the males of certain Ephemeridae 

 and in both males and females of Blepharocera capitata. 



The eyes of our Blepharocera are plainly divided, or are two 

 on each side (Fig. 3, A and B). One of these eyes is dark 

 colored, has small facets, and faces anteriorly and laterally. 

 It is fairly convex. The other is reddish-brown, is composed 

 of much larger facets, faces dorsally and has a nearly flat sur- 

 face. This red, large faceted dorsal eye has the appeai-ance of 



