Dec., 1906.] North American Species of Tabanus. 
2 I 
them. These males with numbers of females from the same 
locality are types of a species described below under the name 
Tabanus stenocephalus in refenrence to its very small head when 
compared with some other species that are much like it in 
general appearance. 
The males of many, perhaps of all the species of Tabanus 
spend much time flying in the sunshine, but the habit of hover¬ 
ing appears to be confined to a few, may be to those with the 
small head sand uniform sized facets. Those that do not hover 
flv so rapidly that the eye cannot follow them, but one is apprised 
of their presence by recognizing the sound of their wings. Now 
and then they alight for an instant on some weed or bush, or 
sometimes on the ground, after which they continue as before. 
By including all the species with a uniform middorsal gray 
band, a few are brought in that are more or less aberrant to the 
group, consequently at least three treated in the present paper 
do not appear to be closely associated with the others. 
No doubt students will find it difficult to separate out the 
species falling here, especially if they happen to possess only one 
or two out of the fifteen or more known. 
The following key is offered as an aid, and in every instance 
does not make use of characters which are considered the most 
specific, but such as are most likely to be found with the usual 
limited number of specimens at hand: 
1. Posterior femur uniformly reddish for its entire length. 2. 
Posterior femur black or at least blackish on basal part. 8. 
2 . Wings wide, a distinct brown spot on the furcation of the third veir. 
acutus Bigot 
Wings normal, no brown spot on the furcation of the third vein. 3. 
3. A row of rounded gray spots on either side of the middorsal abdom¬ 
inal stripe. 4. 
Three gray or yellow stripes on the dorsum of the abdomen, lateral 
stripes abbreviated. 5. 
4. Costal cell fuscous, a single green band on the eye in life. 
fuscicostatus n. so. 
Costal cell dilute yellow, two green bands on the eye in life, sagax O S. 
5. Eyes pilose, very plainly so in the male. gua.emalanus n. sp. 
Eyes not pilose. 6. 
(i. Abdomen reddish, branch of the third vein without an appendage. 
carneus Bellardi 
Abdomen fuscous, branch of the third vein with an appendage. 7. 
7. Thorax yellowish. trilineatus Latr. 
Thorax fuscous. appendiculatus n. sp. 
8 . Abdomen with a gray middorsal stripe and rounded lateral spots, 
costal cell fuscous. fuscicostatus n. sp! 
Lateral markings of the abdomen not in the form of rounded spots. 9. 
9. Abdomen with a middorsal stripe and oblique lateral spots which are 
angular and contiguous. lir.eola Fabr. 
Lateral markings of the abdomen linear. 10. 
10. Thorax dark or nearly black. 11. 
Thorax gray or yellowish. 15. 
