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MEMOIRS OF THE XATIO^'^AL ACADEMY OF SCIENCES. 
IX.— A RATIONAL NOMENCLATURE OF THE VEINS OF INSECTS, ESPECIALLY THOSE OF LEPIDOPTERA. 
Hitherto there has been an nnfortnnate lack of uniformity in the nomenclature of the veins 
of the wings, different names having been applied to the veins of different orders of insects. 
In his ]niper on the phylogeny and ontogeny of the veins of the wings of Lepidoptera, Si)uler 
has, however, given us a simple scheme and a numbering of the veins which will, we think, apply 
in general to the wings of insects of all orders. 
Kedtenbacher had previously pointed out that ^Hlie geologically older Orthoptei^a and 
Neuroptera have a iniicli richer and more complicated venation than the Coleoptera, Le 2 ndox)tera, 
Hymenoptcra, and Diptera; thus among the Rhynchota the oldest forms, the Cicadidm and 
Fulgoritbe, have a much greater number of veins than the Ilemiptera. There is no doubt but 
that the oldest insects were provided with an excess of veins; that, on the other hand, in the course 
of development this superfluity has disai) 2 )eared by a process of reduction, and in this wa 3 ^a simpler 
system* of venation has resulted. It is also to be observed that the size of the wings has had a 
considei’able influence on the number of the veins, since small forms almost without exception 
have fewer veins than insects with large wings,” RLMltenbacher also believes ‘^that the normal 
type of a differentiated wing may be found in those insects whose fore and hind wings are most 
similar in size and shape,” and states that the venation is not useful as an ordinal character, but 
is of more service iu separating suborders and families. 
We agree with Spuler iu rejecting Redteiibacher’s system, which is partly based on Adolph’s 
untenable theory of convex and concave veins, but more esi^ecially for the reason that 
Redteubacher assumes that the primitive form of venation is that of the EiMiemerida?. He 
remarks: “There is scarcely another group of insects whose wings show the i^riinitive type, the 
fan-shaped form, as the Alay Hies.” It may be objected to this that the E 2 )hemerida‘, though iu 
most respects generalized and primitive insects, yet are, as regards the wings, highly modified or 
specialized. That this is the case is also suggested by the i‘eduction or atrophy of the mouth 
parts. On the other hand, the retention of sexual organs paired throughout, the ducts remaining 
separate, Avith open, i^aix'ed outlets, shows that the May flies are, iu this respect, more primitive 
than any other winged insects. Rut as regards the thorax and the wings, Av^e observe that iu 
them a high degree of modification has taken place. Thus the two itaxTS of wings are A’ery unlike 
in size and shape, and this feature is a secondary one. Heuce the large number of main 
longitudinal A^eins in the wings of Ei)hemera is a case of irrelative repetition of parts mostly 
.situated in the fan-like field, due to a process of specialization, a process Avhich is manifested in 
.quite auother way iu the Avings of the Dennaptera, also a i^rimitiA^e type. 
■Redteubacher regards the eleven longitudinal veins (I-XI) of Ei)hemerids as the normal 
.number, and considers that the Trichoptera, Lepidoptera, etc., have lost certain of the veins by a 
jjH'ocess of reduction. This view has been adopted by Comstock in his suggestive paper, 
“Evolution and taxonomy,” but it seems to us to be Ainteuable, the anal held (“faltentheil” of 
-Spuler) not being of primary inqAortance. On the other hand, Redtenbacher’s use of Roman 
numerals for the main veins, and of a combination of Roman and Arabic numerals for their 
branches, is very couA^enieut. 
Spuler divides the wings of each pair into an outspread portion {SpreitentheiJ) and a folded 
part {Faltentheil). The A'eius of the former area he numbers iu the same manner as Redtenbaclier, 
beginning on the costal edge of the Aving, Avbilo those of the folded area (the submedian and 
internal or first and second anal veins of other authors) he does not name, but simply luimbers 
with the Grreek letters a ft. He considers that Hagen was rigid in believing the Phryganidm, 
Tipularim, and some Microlepidoptera to be forms Avith a schematic, i. o., inimitiA’e A'euatiou 
(Stettin. Ent. Zeit., p. 31G, 1870). 
Spuler shares the opinion of Fritz Midler (Termitidai), Brauer and Redteubacher (Libellulida?), 
:and Haase (Papilionidai), that the costa is only a hyiio^lermal structure, a thickening of the edge, 
which does not liave a trachea as its origin (Anlage), and Avhich therefore has nothing to do with 
the A^eins. 
