Z TRIBE 1SIEMATINA. 



This is a very extensive sub-family. It is more espe- 

 cially characteristic of the northern parts of the False - 

 arctic and Nearctic regions ; and the species decrease 

 very much from the north to the south of these zones. 

 In fact, the only species known beyond them is one 

 from Chili, which has been referred doubtfully to 

 Dinewra, and another also doubtfully referable to 

 Dineura, is known from Sierra Leone. 



The relations of the group to the Tenthredina have 

 been already discussed (cf. vol. i, p. 64, and p. 185). 

 By Thomson three genera are recognised, namely, 

 Nematus, Cladius, and Leptocercus (= He'michroa), by 

 Zaddach six, Nematus, Euura, Camponiscus, Cladius, 

 Dineura and Hemichroa, while by other authors, in 

 addition to these, Croesus and Pristophora are separated 

 from Nematus, TricJiio campus and Priophorus from 

 Cladius, and Mesoneura from Dineura. Epitactus, Foer. 

 (Yerh. pr. Rhein., 1854, p. 435), is in all probability 

 only an aberration ; it merely differing from Nematus 

 in the third cubital cellule receiving one of the recur- 

 rent nervures, a form of neuration which occurs with 

 many Nemati that have the second recurrent ner- 

 vure interstitial, e.g. N. caprece.* 



The genus Diphadnus, Hartig (Blattw., 225), has 

 only two cubital cellules, the body compressed, oval, 

 and Selandria - like. I have examined a German 

 example of D. fuscicornis, and am inclined to believe 

 that the absence of the third transverse cubital ner- 

 vure may not be constant. In general structure and 

 coloration the species comes very near to N. appendi- 

 culatus, and the form of the abdomen is very similar 

 to what exists with Dineura despecta. An examination 

 of a large number of specimens can alone settle the 

 affinities of the group. Cf. also Stein, Ent. Nach., 

 vii, p. 63. 



For reasons stated further on I adopt seven genera, 

 and these may be separated as follows : 



* An analogous case occurs in species of Hylotomina and in some 

 Selandriades, e.g. Selandria sixii. 



