8o6 



THE AMERICAN NATURALIST. [Vol. XXXVIII. 



believe that this persists as the antennal sclerite of Comstock 

 and Kochi. In embryos about ready to emerge these annular 

 sclerites are very clearly marked, and allow of no question as to 

 their equivalence to other sclerites. 



There has been much discussion as to the origin and signifi- 

 cance of the hypopharynx, though the data have been drawn 

 almost solely from a study of comparative anatomy. Apparently 

 the majority of those who have thus studied it regard it as repre- 

 senting a fused pair of appendages. Vayssiere ('82) who worked 

 upon krval Ephemeridae, strongly favored this view, though he 

 adds that in order to settle the question studies of a number of 

 representatives of the various orders would be necessary. 



Folsom (:oo) derives the hypopharynx of Anurida from a 

 median unpaired evagination between the first maxillae, and two 

 small papillae between the mandibles. The first gives rise to 

 the lingua, while from the latter are developed the superUnguae. 

 The superlinguae Folsom regards as the appendages of a dis- 

 tinct segment, provided with a small ganglion. He brings for- 

 ward much evidence from comparative anatomy to show that the 

 hypopharynx of Anurida is typical of the Apterygota. Further 

 than that, he attempts to apply the same interpretation to the 

 Pterygota. 



The only worker who has devoted any attention to the embryo- 

 logical development of the hypopharynx of the Ptergota is Hey- 

 mons ('95a). This investigator reached the surprising conclusion 

 that the hypopharynx represents the fused sternites of the mouth 

 part segments. That this interpretation is essentially correct 

 m\ studies haxe convmced me. However, I would not attribute 

 to the labial sternite any part in this structure. I believe that 

 tile hypopharynx of Blatta represents the fused sternites of the 

 mandibular and first maxillary segments (Fig. 12, hyp.), and that 

 <>t a consequence of the forward migration of the mouth parts 

 these fused sternites have been pushed to within the mouth 



I'l I^latta. then, the sternite of the labial segment is repre- 

 sented . .nly by the ventral cervical sclerites. It seems to me very 

 cear that C omstock and Kochi are right in regarding the gula 

 <>t ( oleoptera and certain other insects as renresentinff the fused 



