52 AMERICAN BLACK FLIES OR BUFFALO GNATS. 



This description fits meridionale in practically every respect, 

 except that the form of the tarsal claws is not indicated. Though 

 the outer stripes are given as " not curved outward at posterior end,*' 

 they appear to represent a form often met with in this species, where 

 the apices of the side stripes are indistinct. I consider it highly 

 probable that this is merely a synonym of meridionale Riley, but I 

 have not seen the types, and there are no disadvantages to be appre- 

 hended from retaining tamaulipense as a possible distinct species 

 until some one examines the original specimens. 



Simulium griseum Coquillett. 



Female. — Opaque gray-brown; frons and face thickly white-gray 

 dusted; antennae brown, the basal two joints and base of third yel- 

 low; palpi brown-black. Scutum gray-brown, very thickly covered 

 with white dusting except on center, where there is a more or less 

 distinct longitudinal stripe, and on lateral and posterior margins, 

 where the ground color becomes yellowish; pleura? gray, paler 

 posteriorly; scutellum yellow; postscutum gray-black. Abdomen 

 tawny yellow, first five segments with a rounded, opaque black, 

 dorso-central spot, that on the segment beneath basal scale the least 

 distinct, remaining segments yellow with slightly darkened dorsum ; 

 sometimes in addition to the central spot there are indications of lat- 

 eral spots on the first four segments. Legs yellow, black as follows : 

 Mid and hind coxae ; entire fore tarsi ; hind femora ; hind tibiae ; 

 basal three joints of both mid and hind tarsi at apices; and last two 

 joints of mid and hind tarsi entirely. Wings clear, thick veins yel- 

 lowish. Halteres yellow. 



Frons divergent-sided, its width at upper angle of eyes equal to 

 its length from lower to upper angle and one-fourth wider than at 

 lower angle, surface hairs yellow; face as long as frons, subquadrate, 

 surface hairs yellow; postocular cilia pale. Scutum with pale yel- 

 low pilosity which is regularly distributed and elongate scale-like, 

 short except on posterior margin; viewed from behind there is an 

 indication of two white spots on the anterior margin of scutum at 

 the inner angle of prescutum ; pleural tuft yellow ; hairs on scutellum 

 yellow. Abdominal basal scale yellow and yellow-haired; surface 

 hairs on abdomen yellow. Legs with pale yellow pilosity and a few 

 scattered upright brown hairs which are most noticeable at apices 

 and on dorsal surfaces of tarsal joints; basal joint of hind tarsi with 

 apical extension, second Avith basal scale and constriction, claws as 

 shown in Plate II, figure 7 {venustum). Wing venation normal, 

 hairs on wing base not numerous, yellow. 



Length, 1..5-2 mm. 



