8 ILLINOIS BIOLOGICAL MONOGRAPHS [326 



Linnaeus in the fourth edition of the Systema Naturae (1744) estab- 

 lished the order Hymenoptera under the name of Gymnoptera and applied 

 to the order its present designation in the first edition of the Fauna Suecica. 

 The name Piezata was proposed by Fabricius (1775) for the order, but 

 this name never came into general use. Latreille (1796), following Lin- 

 naeus, divided the order into two sections, Terebrantia and Aculeata. 

 The first section included two groups, Phytophaga, which comprises the 

 Tenthredinoidea, and the Entomophaga or parasitic Hymenoptera. The 

 Ditrocha and Monotrocha of Hartig (1837) correspond approximately 

 with the two sections of Latreille. Gerstaecker clearly recognized the 

 Tenthredinoidea as a unique compact group and proposed in 1867 to 

 divide the order Hymenoptera into two suborders. He used the name 

 Symphyta for the Tenthredinoidea and Apocrita for the remainder of the 

 order. The term Symphyta thus antedates Konow's (1890) subordinal 

 name Chalastogastra. Various terms have been proposed for this group 

 of Hymenoptera and the following are coextensive with the superfamily 

 name Tenthredinoidea as used in the present paper: Phytophaga, Ses- 

 siliventres, Securifera, Serrifera, Symphyta, and Chalastograstra. Rohwer 

 and Cushman (1917) proposed a third suborder of Hymenoptera, Idiogas- 

 tra, for the family Oryssidae and placed it between the Chalastogastra and 

 Clistogastra of Konow. 



Early students of the Tenthredinoidea divided the superfamily into 

 two groups, Phyllophaga for the Tenthredinidae or "Tenthredo" of 

 Linnaeus and Xyllophaga for the Siricidae or "Urocerus" of Geoffroy. 

 With the exception of Stephens (1835) and Andre" (1879), who recognized 

 the additional families Xiphydriidae and Cephidae, respectively, besides 

 the two families mentioned above, the old system was followed for many 

 years. With the progress in studies of the world fauna of this group 

 of insects, modern writers h<ave proposed many elaborate schemes of classi- 

 fication. Konow in 1890 suggested one family and three subfamilies and 

 Dalla Torre (1894) catalogued one family divided into eighteen subfamilies, 

 while Ashmead (1898) proposed fifteen families and twenty-seven sub- 

 families. Enslin (1911) criticized Konow's three divisions as unnatural 

 and proposed four families, Oryssidae, Siricidae, Cephidae, and Tenth- 

 redinidae, thus reverting to a considerable extent to the scheme of the old 

 school as represented by Cameron (1882) and others. The recent and 

 more important systems are those proposed by Konow (1905), MacGilliv- 

 ray (1906), and Rohwer (1911). These systems, when compared, show a 

 great discrepancy in the number and rank of the groups which formerly 

 constituted the family Tenthredinidae, as is indicated graphically in 

 Plate XIV. MacGillivray, whose classification is based on a thoro-going 

 phylogenetic study of the wings, is of the opinion that the large complex 

 of genera obtained in this family are readily separable into a number of 



