EEV. A. E. EATON ON EECENT EPHEilERlD^ OK MAYFLIES. 191 



and their neuration colourless ; the iutercalar veiulets of the terminal margin in 

 pairs. 



S . Thorax, sternum, and abdomen above pale ferruginous ; venter pale yellowish or 

 greenish ; femur of the fore leg always more or less ferruginous. Length of body 2"5-4 ; 

 expanse of wings 8-10*5 ; setae, d 4*5-5 -5, 2 3-4!*5 mm. (After Walsh.) 



Hab. Kock Island, 111. (Walsh). 



? Cloeon Oldendorfpii, Weyenbergh. 



Oxycypha 0/dendorffii, Weyeub., Tijdsclir. v. Eiit. sxvi. 1882-3, p. 173, pi. x. 6 (1883; [wing]. 



Imago {living). — Eyes dark brown ; head and thorax glossy sepia-brown, the colour 

 changing to fallow-grey on the scutellum [schildje] and passing into a greyish brown on 

 the dorsum of the abdomen. Underside of the body of a very light colour. Setae 

 translucent, light grey. Legs grey. Wings vitreous, with dark nem-ation ; the sub- 

 marginal area in the figure is shaded, and two straight cross veinlets, remote from 

 one another, are shown in the pterostigmatic space, lludimentary intercalar veinlets 

 of the tei'minal margin of the mesothoracic wing paired. No mention is made of hind 

 wings. Length of body 5-5*5, wing 4*75, setae 6 mm. 



Hab. Cordova, Argentine Hepublic ; in the autumn, found at rest on walls. (After 

 Weyenbergh.) 



CALLIBiETIS, Etn., 1881. 



Illustrations. — Adult (details), PI. XVI. 28 a-d ; (whole figures) see citations of Pictet 

 (1843-5) under C. tmdatus and C.fasciatus. Nym/ph, PL XLVIII. 



Adult. — Hind wing oblique, widened rapidly in front from the roots to the costal pro- 

 tuberance, usually rather broad, and oblong, with the tip ellipsoidally rounded off ; costal 

 protuberance large and very obtuse ; neuration limited to three main longitudinal 

 nervures, a few rudimentary intercalars from the terminal margin between the second and 

 the third of these, and (at least in the marginal area) a considerable number of cross 

 veinlets. Fore wing in the majority of the species variegated in one or both of the sexes 

 in front, and sometimes in the disk ; but in others without colour-ornamentation ; cross 

 veinlets numerous throughout the whole of the marginal area, and either pluriserial 

 in the disk or arranged in a few dislocated series, as in Baetis ; rudimentary intercalary 

 veinlets of the terminal margin single or paired, according to the species. Forceps-limbs 

 of 6 conformable to those of Cloeon. Penis not observed hitherto. Of the ? abdominal 

 segments 6-9 are a little the longest. Caudal setae of 6 im. 2-2^, ? im. l^i as long 

 as the body. Fore tarsus of 6 about 1-^- fis lo^o ^^ the tibia, which is nearly 1^ as long 

 as the femur ; its joints in diminishing succession rank 2 subequal to 3, 4, 5, 1. Fore 

 tarsus of $ about -f as long as the tibia, which is about as long as the femur ; its joints 

 in order of lessening length rank 2 subequal to 5, 4, 3, 1. Hind tarsus of 6 about \ as 

 long as the tibia ; its joints rank 1, 4, 2, 3. Nijnipk. — Abdominal tracheal branchiae all 

 iouble, with unequal divisions : the first and second are each formed of a large somewhat 

 Dblong lamina obtusely rounded at the tip, contracted transversely in some measure about 

 aaidway from the roots, and slightly contorted, connate with a smaller underlying division 



