2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, I46 



ala) whether on an insect, a bird, a bat, an angel, the devil, or an 

 airplane. 



Of course, the early nomenclators made some mistakes in identi- 

 fying organs of insects from comparison to vertebrates. For ex- 

 ample, they called the cellular layer of the body wall below the 

 cuticle the "hypoderm," whereas it really corresponds with the epi- 

 dermis of the vertebrate. The preoral space between the mouthparts, 

 which are modified legs, they regarded as the mouth cavity of the 

 insect and called the food pocket over the hypopharynx, now known 

 as the cibarium, the "pharynx," whereas a true pharynx is postoral 

 and is an anterior part of the alimentary canal. Incidentally, they have 

 left us the incongruous terms of epipharynx and hypopharynx for 

 preoral structures which have no relation to the pharynx. 



A notable misnomer in insects is the term "suture" commonly given 

 to the grooves of the exoskeleton that form strengthening internal 

 ridges. The word suture can mean only a seam (sutura) or line of 

 union between adjoining parts, and undoubtedly it was suggested to 

 the early entomologists by the sutures of the vertebrate skull. The 

 word suture has a specific meaning that could be applied to any line 

 of union, but cannot be made to mean anything else. It is a distortion 

 of its meaning to apply it to a surface groove formed by inflection 

 of the cuticle. Of course, it is only in a figurative sense that any- 

 thing in anatomy may be called a suture. The only true anatomical 

 sutures are those made by surgeons. 



Another misnomer, now thoroughly established, is the application 

 of the term chorion to the insect eggshell despite the fact that this 

 shell is secreted by the ovarian follicle, whereas the vertebrate chorion 

 is a cell layer proliferated by the embryo. 



It seems better to live with these incongruities than to attempt 

 to rectify all of them. After all, everyone has some concept of the 

 meaning of terms such as mouth, heart, leg, etc., and the only per- 

 sons likely to be concerned with the differences between, for instance, 

 vertebrate and invertebrate hearts are those who know the differ- 

 ences. They will not be confused by using a term such as heart for 

 several nonhomologous structures of different animal phyla. 



Body segmentation: The primary body segments of an adult 

 insect are the annular sections of the integument marked by the lines 

 of attachment of the longitudinal muscles. A body segment literally 

 should be a somite (soma -\- ite), but preliminary to body segmen- 

 tation there are formed corresponding pairs of cavities, the coelomic 

 sacs, in the mesoderm. Some embryologists, as Manton (1949), de- 



