212 EEV. A. E. EATON ON EECENT EPHEMElilD^ OR MAYFLIES. 



? . Wings free from the basal discoloration, and nearly so from the specks noted 

 in d , but yet with dark-bordered cross veinlets. Fore leg in opaque view pitch-brown, 

 in some lights intense bistre-brown, paler at the base and at the knee, but not dark- 

 banded. Hinder femora raw-umber brown, with a single ill-defined dark band before 

 the knee. Setse light Cologne-earth brown, with the joinings and bases of an intense 

 shade of the same colour or piceous. Abdomen discoloured : the median dorsal stripe 

 apparently is represented by a longitudinal line on each side of the track of the dorsal 

 vessel, and the lighter blotches seem to be less conspicuous than in the d : instead of the 

 ventral dashes and dots of the other sex, the $ has only small, conspicuous twin oval 

 dark-edged spots in the places of the ganglia. Length of body 11-12; wing, 6 13, 

 ? 14 ; setoe, d im. about 17, $ im. 13 mm. 

 Sab. Colorado (M'^Lach. Mus.). 



Ameletus exquisitus, sp. nov. Plate LXIV. 24 (forceps-basis). 



Imago (dried), d . — Mesonotum brown-ochreous ; metanotum pitch-brown. Abdomen 

 in segments 2-6, and sometimes in a large part of 7, translucent at the sides : the dorsum 

 in these segments, in a large measure tinged with a rich brown-ochre, is bordered along 

 the tei'minal margin with light pitch- or with Vandyke-brown, this darker colour occu- 

 pying the hinder lateral angles of the segments so as to form a series of right-angled 

 triangular spots extending each from the hind margin of the segment to the point of 

 origin of the segmental trachege ; the tracheae themselves are slightly brownish ; again 

 from the dark terminal border in every segment two slender streaks issue basewards, one 

 on each side of the median track, which in ill-marked specimens are represented by small 

 triangular spots only, at the border in question. The remaining dorsal segments are 

 more opaque than the preceding, but are marked in a nearly corresponding manner with 

 the same darker colour, excepting the terminal segment, which is almost uniformly of the 

 lighter colour. Venter in segments 2-6 translucent, and (like the translucent portions 

 of the dorsum) of a somewhat light bistre-grey colour ; in segments 7-9 very light 

 brownish ochre ; the ganglia brownish, and the forceps-basis tinged at the lateral borders 

 with bistre-brown. Eorceps-limbs pitch-brown. Seta? warm sepia-brown, dark at the 

 joinings throughout, and also dark near the roots. Fore leg in opaque view pitch-brown, 

 with the knee yellowish brown. Hinder femora bistre-brown in opaque view, with a dark 

 prseapical band ; the tibiae and tarsi in opaque view light bistre- or raw-umber brown, 

 with the ungues opaque, or sometimes the tarsi are sepia-brown ; in transmitted light 

 the tibiae and tarsi acquire a yellowish tint, seldom approaching brownish or dark yellowish 

 umber. Wings vitreous, tinted almost imperceptibly with bistre-grey throughout ; the 

 pterostigmatic portion of the fore wing transparent bistre-brown : neuratiou in opaque 

 view dark bistre-brown, in oblique view almost raw-umber, but somewhat of a redder 

 brown ; in transmitted light translucent rufo-piceous ; cross veinlets of the pterostigmatic 

 portion of the marginal area of the fore wing branched evenly near the costa, and 

 regularly anastomosing with one another. Length of body, d im. 14, wing 16 : setae 

 defective. 



