134 EEV. A. E. EATON ON EECENT EPKElMEEID-i: OE MAYFLIES. 



than the thorax, the dorsum tuberculated as in Ephemerella, the venter convex ; insertion 

 of antennae intermediate between the anterior ocellus and the sides of the face ; palpus 

 of maxilla I. lost (or aborted ?) in the specimen examined ; tracheal branchiae borne by- 

 segments 1 & 4-7 arranged as in C<enis. — Body broadest at about the fifth abdominal 

 segment, narrowed thence towards the thorax and tails ; abdomen oniscoidal, the 

 segments very similar in form to those of Nymph 'Ko. IV, having the intermediate 

 pleurse produced in like manner into curved acuminate retrorse serratures (which are 

 spinulose along their front edges and beset with long, fine scattered hairs), but having a 

 series of uncinate tubercles on each side of the median line of the dorsum, extending 

 from the first to the sixth segment, the tubercles standing singly at the hinder edges of 

 the segments pointing backwards, and represented in the following three segments by 

 small marginal teeth. Caudal setae acutely and narrowly plumose, about f as long as 

 the body. Pronotum transverse, quadrangular with almost straight sides, about as broad 

 as the head in front, and very little broader behind. Legs very like those of Ephemerella. 

 Tracheal branchiae of segment 1 minute, erect, 2-jointed, Avith the first joint short and 

 the second joint more slender, filiform, and distally pilose or pubescent, arising from the 

 dorso-pleural region rather behind the middle of the segment and near the lateral borders ; 

 those of segments 4-7 inserted in sinuses at the hinder bases of the pleurae, and com- 

 posed, like those of Ephemerella, each of a lamina sheltering lamellae, but differing from 

 their homologues in that genus in being compactly stratified rather than imbricated, 

 those of segment 4 elvtroidallv shielding the others. Moreover, the branchial laminae 

 of at least segments 4-6 are each traversed by a crease from side to side, situated at about 

 f of the distance from the roots to the tip ; and while the foremost is pergamentose in 

 texture, all the other laminae are papyraceous or membranous ; whereas in the genus 

 quoted the laminae are not creased, and only the hindermost in each series is papyraceous. 

 The laminae diminish successively, chiefly in length ; their form in segment 4 is narrowly 

 suboval, somewhat abrupt at the base ; in segment 5 each is broadly oval, truncate at 

 the base ; in segment 6 the laminae are rotundate-subquadrate ; the hindermost are 

 almost semi-rotund. Length of body, 6 12, setae 5 millim. 



Kah. Detroit, Mich. (Mus. Comp. Zool. Cambridge, ]\Ias.) ; M'CoUam's Lake, M'Henry, 

 111. (May ; Foster in Mus. State Lab. Nat. Hist., 111.). The eyes of the adult must be 

 ascalaphoid ; but the hind wings of the nymph differ from those of described genera of 

 this section. 



TELOGANODES, Etn. 1882. 



Illustrations. Adult (wings), PI. XV. 24 bis. 



Adult. — Hind wing minute, obovate-oblong, angular in front nearly in the middle, 

 with the apex of the angle inverted, and with the margin beyond the angle slightly 

 concave ; ncuration very simple, consisting of the subcosta (2), radius (3), cubitus (5), 

 and praebrachial (6), with or without a sector, and with scarcely a cross veinlet ; subcosta 

 nearly straight, terminating abruptly near the salient angle without meeting the costa ; 

 the common stem of the radius and cubitus makes an acute angle with the subcosta, and 

 is met by the cubitus at a distance of about ^ of the wing's length from the wing-roots; 



