NATURAL SCIENCES OE PHILADELPHIA. 199 



II. 



I. 



One radial area. 

 Antennae, 14-jointed. 

 No distinct pulvilli. 

 Ungues, with, distinct teeth on the un- 

 derside. 

 No spurs at the tip of the tibiae. 

 Limn obi a 710b. 



Two radial arese. 



Antennae, 16-jointed. 



Pulvilli distinct. 



Ungues smooth on the under side. 



Tibiae, with spurs. 



Limnophila 



nob., etc. 



Tibiae, without 



spurs. 

 Erioptera 



Meig., etc. 



These characters do not exhaust the contrast : the structure of the mouth, 

 and that of the male genital organs, is different in both groups. 



The first column, and the two subdivisions of the second, contain thus the 

 characters of the three principal groups of the tribe. Among the 87 species 

 described on the following pages, 68, that is, nearly four-fifths of the whole 

 number, belong to these three groups, each of them containing about the same 

 number of species. I will call them Tipulae limnobiaeforra es (with 24 

 species), Tipulae eriopterae formes (with 25 species), and Tipulae lim- 

 nophilaeformes (with 19 species), thus deriving the names from those of 

 the typical genera. 



A fourth group has all the characters of the second, as enumerated above, 

 except that the structure of the antennae is anomalous ; they have 6, some- 

 times 10, distinct joints, and often reach extraordinary proportions, being in 

 the rj 1 of some species three or four times longer than the body. Some other 

 characters, as the structure of the palpi, the presence of a tubercle on the 

 front, etc., justify the separation of this group. A fifth group also answers to 

 all the characters of the second ; but has, besides, a mediastinal cross-vein, 

 which is far remote from the tip of the mediastinal vein, and anterior to the origin 

 of the petiole ; pubescent eyes; a distinct tubercle on the front, behind the antenna, 

 and the 4th joint of the palpi elongated ; I call them Tipulae pediciaeformes. 

 The structure of the rj 1 genitals and the neuration of the wings, (especially the 

 form of the discal areolet) in this group, seem'to indicate a transition towards 

 the Tipulos with long palpi. The genera Amalopis and P e d i c i a are the 

 types of /the group ; Dicranota is closely related to them, although it has 

 13-jointed antennae and short palpi ; Ula is only provisionally placed in this 

 group on account of its pubescent eyes, the position of its mediastinal cross- 

 vein, etc. 



We have seen that the first group reproduces the characters enumerated 

 above in the first column ; that the second and third group answer to the 

 characters of the second column ^ the fourth and fifth group, although some- 

 what anomalous, show a decided prevalence of the characters of the second 

 column. But there are several genera which possess some of the characters of 

 ihefirst and some others of the second column at the same time, so that they have 

 no more relation to the one than to the other. They have, for instance, one 

 radial area and 16 (instead of 14) joints of the antennce; the structure of their 

 genital organs holds also the middle between the typical forms of the first and 

 second group, with more apparent analogy to the second. But besides this 

 anomalous combination of characters, each of these genera shows some pecu- 

 liarity of structure, for the most part, so striking, that it appears at once very 

 natural to isolate them from all other groups. I have gathered them all in a 

 sixth group, which I have placed between the first and the second, under the 

 name of Tipulae anomalae. This -group is entirely artificial, and, for this 

 reason only provisional.* 



* It will be seen below, that the four genera placed in the group alluded to, have all 

 one radial area and spurless tibim. But, among the species of my collection, which re- 

 mained undcscribed on account of too small number of specimens, there is one which 

 has one radial area and distinct spurs at the tip of the tibim, and thus combines again the 

 characters of the two opposite columns. 



1859.] 



