The Comstock–Needham system is a naming system for insect

wing vein Insect wings are adult outgrowths of the insect exoskeleton that enable insects to fly. They are found on the second and third thoracic segments (the mesothorax and metathorax), and the two pairs are often referred to as the forewings and hin ...

s, devised by John Comstock and George Needham in 1898. It was an important step in showing the homology of all insect wings. This system was based on Needham's ''pretracheation theory'' that was later discredited by

Frederic Charles Fraser ''For others uses see Frederick Fraser (disambiguation)'' Frederic Charles Fraser (15 February 1880, in Woolwich – 2 March 1963, in Linwood was an English entomologist who specialised in Odonata. Following army service in India as a sur ...

in 1938.Fraser, F. C. 1938. A note on the fallaciousness of the theory of pretracheation in the venation of Odonata. ''Proc. Roy. Ent. Soc. London'' (A) 13: 60–70

Vein terminology

Longitudinal veins

The Comstock and Needham system attributes different names to the veins on an insect's wing. From the

anterior Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

(leading) edge of the wing towards the posterior (rear), the major

longitudinal Longitudinal is a geometric term of location which may refer to: * Longitude ** Line of longitude, also called a meridian * Longitudinal engine, an internal combustion engine in which the crankshaft is oriented along the long axis of the vehicle, ...

veins are named: *''costa'' C, meaning ''rib'' *''subcosta'' Sc, meaning ''below the rib'' *''radius'' R, in analogy with a bone in the forearm, the

radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...

*''media'' M, meaning ''middle'' *''cubitus'' Cu, meaning ''elbow'' *''anal veins'' A, in reference to its posterior location Apart from the costal and the anal veins, each vein can be branched, in which case the branches are numbered from anterior to posterior. For example, the two branches of the subcostal vein will be called Sc₁ and Sc₂. The radius typically branches once near the base, producing anteriorly the R₁ and posteriorly the ''radial sector'' Rs. The radial sector may fork twice. The media may also fork twice, therefore having four branches reaching the wing margin. According to the Comstock–Needham system, the cubitus forks once, producing the cubital veins Cu₁ and Cu₂. According to some other authorities, Cu₁ may fork again, producing the Cu_1a and Cu_1b. As there are several anal veins, they are called A1, A2, and so on. They are usually unforked.

Crossveins

Crossveins link the longitudinal veins, and are named accordingly (for example, the medio-cubital crossvein is termed m-cu). Some crossveins have their own name, like the

humeral The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a ro ...

crossvein h and the sectoral crossvein s.

Cell terminology

The cells are named after the vein on the anterior side; for instance, the cell between Sc₂ and R₁ is called Sc₂. In the case where two cells are separated by a crossvein but have the same anterior longitudinal vein, they should have the same name. To avoid this, they are attributed a number. For example, the R₁ cell is divided in two by the radial cross vein: the basal cell is termed "first R₁", and the distal cell "second R₁". If a cell is bordered anteriorly by a forking vein, such as R₂ and R₃, the cell is named after the posterior vein, in this case R₃.

References

External links

North–Carolina state University course on insect wings
{{DEFAULTSORT:Comstock-Needham system Insect anatomy Conceptual systems