262 DIPTERA OF NORTH AMERICA. [PART IV. 



third branch of the fourth vein ; the marginal cross-vein is at, or 

 very near this tip. The prsefurca, the origin of which is about 

 the middle of the length of the wing, is rather long, arcuated or 

 angular near the basis (in the latter case generally with a stump 

 of a vein) ; its further course is generally straight, in a line with 

 the third longitudinal vein. The relations between the two 

 branches of the second vein, the third vein, and the small cross- 

 vein are very peculiar in this genus, and deserve a particular 

 attention (compare the figures 14 and 15 of Tab. II) : 1. The 

 small cross-vein always connects the fourth longitudinal vein with 

 the second vein or the posterior branch of this vein ; never with 

 the third vein, as is almost universally the case among the 

 Diptera ; in other words, the third vein in the genus Amalopis 

 (at least in all the instances observed by me) always issues from 

 the second beyond the small cross-vein. Hence, it is a peculi- 

 arity of Amalopis (and this applies also to Pedicia), that the 

 second submarginal cell is never longer than the first posterior 

 cell, generally a little shorter. From among all the other 

 Tipulidse, I am aware of two genera only, where the position 

 of the small cross-vein, above alluded to, is to be met with : 

 Ptychoptera and Bittacomorpha. Even in Erioptera (subg. 

 Molophilus, compare Tab. I, fig. 19), the venation of which 

 otherwise reminds of Amalopis, the small cross-vein has the 

 usual position, between the third and the fourth veins. 2. The 

 first submarginal cell is either shorter than the second, which is 

 the normal venation among the Tipulidse ; or it is longer than 

 the second submarginal (Tab. II, fig. 14), a form of venation 

 occurring also among the Eriopterina of the subgenus Molophilus 

 (see Tab. I, fig. 19), and the Ptychopterina (Tab. II, fig. 19, 20). 

 We might express the difference between these two forms of vena- 

 tion by saying that, in the first case, the second vein is forked, in 

 the second case, the third ; but this would be a deviation from 

 the terminology adopted by us and according to which it is 

 always the second and never the third vein which bears the fork. 

 The first submarginal cell is longer than the second in the 

 American species A. hyperborea, vernalis, calcar, and the 

 European species A. unicolor Schum. and immaculata Schum.) ; 

 the first submarginal cell is shorter than the second in A. 

 auripennis 0. S., in the normal specimens of A. inconstans 



