Ko. 1438. WINGS OF THE TENTHREDINOIDEA—MacGILLIVRAY. 573 



margin of the wing-, the}^ are costa nnbranched, subcosta with two 

 In-anches, radius with tive branches, media with four l)ranches, cubitus 

 with two branches, and three unbranched anal veins. 



Third. That the moditication in the numbei* of wing veins of insects 

 has proceeded along two distinct lines, the specialization of wing veins 

 by reduction and the specialization of wing veins by addition. The 

 former is illustrated by the wings of the orders Lepidoptera. Diptera, 

 and Hymenoptera; and the latter by the wings of the orders Orthop- 

 tera, Ephemerida, and Neuroptera. 



Fourth. The development of a hypothetical wing type, which was 

 believed to represent the maximum number, the arrangement, and 

 the method of branching of the veins of the primitive insect's wing. 

 This hypothetical type was shown to be of primary importance in 

 determining the homology of the wing veins of insects of all orders. 



The terminology of Redtenbacher had been applied in so many dif- 

 ferent ways by previous investigators that these writers made use of 

 a dilferent system of notation. The}' adopted the names of the stems 

 of the veins as used by Redtenbacher and used abbreviations of these 

 names to designate the veins, Arabic numerals being added as indices 

 to the abbre\'iations for designating the branches of the veins. The 

 abbreviations used were the following: costa, C; subcosta, Sc; radius, 

 R; media, M; cubitus, Cu; and the anal veins as 1st A, 2d A, and 

 8d A. 



In 1902" Enderlein, in a discussion of an abnormal specimen of 

 Telea })olyphemuH gives the results of an extended investigation of the 

 interrelation of the wing and body trachea'. The tracheae of each 

 wing is divided into two systems, the radial and the medial, the 

 former including the costa, subcosta, and radius; the latter, media, 

 cubitus, anal, and axillary veins. It is unfortunate that this writer 

 did not study some of the generalized Lepidoptera, such as the Hepia- 

 lida?. It has been amply proven that in certain of the lower orders of 

 insects, as the Plecoptera, there are two tracheal trunks, the anterior 

 giving rise to costa, subcosta, radius, and media; the posterior, to 

 cubitus and the anal veins. That this was probal)ly the primitive 

 condition in the Lepidoptera is shown ])y the adult wings of certain 

 species of Ileplalux in which media anastomoses with cubitus for a 

 short distance, bends abruptly toward the radius, joins it, and coa- 

 lesces with it to the base of the wing. In most Lepidoptera this basal . 

 connection between media and radius has been lost, but the condition 

 found in Hepkdm would seem to indicate that the arrangement of 

 the veins into systems as shown by Enderlein was probably an 

 acquired one. He has shown conclusively that costa of both wings is 



« Dr. G. Enderlein. Eine einseitige Henimengsbildung bei Telea polyphemus 

 vom ontogenetischen StandiHuikt. Ein Beitrag ziir Kenntniss der Entwicklung der 

 Schmetterlinge. Zool. Jahrb., XVI, 1902. Part 4. 



