A CONTRIBUTION TOWARD AN ENCYCLO- 

 PEDIA OF INSECT ANATOMY 



By Robert E. Snodgrass 



Late Honorary Research Associate 

 Smithsonian Institution 



Insect, Entomology, Hexapoda: An insect, according to the 

 composition of its Latin name {in + sectttm, cut), is literally an 

 "incut," as it is also by its Greek name, entomon ( en + tomos, cut). 

 The study of insects is entomology instead of insectology because 

 the latter involves a combination from two languages. When arthro- 

 pods came to be named according to the number of their legs, as 

 decapods, myriapods, centipedes, etc., the 6-legged insects became 

 hexapods and were classed as the Hexapoda (Gr. liexa, six, + pons, 

 podos, \tg). Hence we call them insects, classify them as Hexapoda, 

 call their study entomology, and call ourselves entomologists (= stu- 

 dents of incuts). 



Anatomical names: The early zoologists who first studied the 

 anatomy of invertebrate animals naturally carried over to what ap- 

 peared to be functionally corresponding organs of the latter names 

 that were long established in vertebrate anatomy. The anatomical 

 names of insect parts, for example, except for a few applied on a 

 basis of analogy, are almost wholly vertebrate names. It thus came 

 about that the same names are applied to parts and organs in verte- 

 brates and insects that can have no possible analogy. However, our 

 whole anatomical terminology would be thrown into confusion if 

 homology throughout the entire Animal Kingdom were made the 

 basis of nomenclature. When organs are named on a functional basis, 

 the same names are applicable to a worm, an arthropod, or a verte- 

 brate. 



A food tract extending through the body, for example, is literally 

 an alimentary canal in any animal in which it occurs. A blood-pump- 

 ing organ is properly a heart regardless of its structure. An ap- 

 pendage for walking is a leg. A head is a head whether on an insect, 

 a snake, a man, or a snail. An organ of flight is a wing (pferon or 



SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 146, NO. 2 



