HORSE-FLIES AND WESTERN AGRICULTURE. 29 



and more widely separated are two small tubercles. On ventral aspect pos- 

 terior to palpal sheaths two small tubercles on each side which normally ap- 

 pear to bear a seta each. 



In the male the rima of thoracic spiracle is curved into a hook at each end. 

 In the female only the anterior end is hooked. 



Abdominal segments 2 to 7 armed with a double circlet of bristles as in Taba- 

 nus punctifer, those on second segment very short. Bristles increasing in length 

 up to seventh segment. 



In the female the dorso-lateral fringe of bristles on the eighth segment just 

 anterior to the terminal teeth is vestigial, and in the male entirely wanting. 

 On the ventral aspect of this segment in the female the fringe of bristles is 

 interrupted on the median line while in the male it is continuous. Of the ter- 

 minal teeth the two lateral ones are most prominent. In the female the lateral 

 teeth are arranged in a straight line with the two dorsal teeth. In the male 

 the dorsal teeth point more directly upward. 



Both larva and pupa were described with the aid of a binocular 

 microscope. 



A NEW SPECIES OF TABANUS. 



A number of Tabanus larvae collected in the mud along mountain 

 rivulets were placed in breeding jars, and one or two adults were 

 reared. These were found by Professor Hine to represent an uncle- 

 scribed species of Tabanus. (PI. IV, A, />, C.) Xo adults of this 

 species were found in Antelope Valley in the open. 



Description of Adult. 6 

 Tabanus monoensis n. sp. 



Length 12 to 14 millimeters. Eyes not hairy, a small, four-sided, nearly de- 

 nuded spot, narrowed anteriorly, on the frontal vertex. Wing with the furca- 

 tion of the third vein and the transverse veins at the apex of the discal cell 

 plainly margined with brown. 



Female (PI. IV. A) : Front at vertex nearly one-third as wide as either eye, 

 narrowed somewhat below, frontal callosity occupying the entire width of the 

 front, shiny black, nearly square, and with a rather obscure connected line 

 above reaching two-thirds of the distance to the vertex. Spot at vertex four- 

 sided, plainly narrowed before, entirely separated from the eyes, very thinly 

 pollinose and without any ocelligerous prominence such as is present in species 

 of Tabanus with hairy eyes. Subcallus plainly pollinose but not so dense as 

 the faee. Palpi white, enlarged basally, pointed below, and clothed with black 

 and white hair. Proboscis uniformly nearly black. Antenna brown, with the 

 annulate portion of the third segment black, first segment prominently en- 

 larged, nearly as wide anteriorly as the base of the third segment; second 

 segment small, more or less hidden between the first and third ; third segment 

 widest at the base, with a small prominence dorsally, then gradually narrow- 

 ing to the annulate portion of the segment, which is pointed at apex and 

 distinctly shorter than the basal portion. Facets of the eyes of nearly uniform 

 size throughout. 



Thorax dark with gray stripes; wing hyaline with the furcation of the third 

 vein and the transverse veins at the apex of the discal cell plainly margined 

 with brown; some of the other veins, especially those having a transverse 

 direction, very obscurely margined with the same color. Legs yellowish brown 

 and black, all the femora black, front tibia yellowish brown on a little more 

 than basal third, remainder black, middle and hind tibiae largely yellowish 

 brown, darkened apically, front feet black, other feet largely dark yellowish 

 brown, darker above than beneath. 



Abdomen dark in ground color with three rows of small gray spots. Hind 

 margin of each segment narrowly gray also. Venter of abdomen partially 

 reddish. 



Male: Like the female in coloration. Compound eyes with small facets 

 around the outside and a large area of enlarged facets on the disk. The dry 

 specimen shows a conspicuous fuscous marking on the middle of each eye which 

 takes the form of a somewhat irregular band across the head, widest at mld- 



a Description by James S. Hine. 



