28 EEV. A. E. EATON ON RECENT EPHEMEEID^ OR MAYFLIES. 



tarsi biunguiculate, the ungues very vinequal (/. c. woodcut h, c). Forceps sliort and 

 stout, their last two joints very short. Length of body, d 36, ? (after oviposition) 32 ; 

 wing, c? and ? , 27 ; seta?, 6 50, ? 17 mm. 



Hab. Near tlie island of EUangowan, in December 1875, in insignificant numbers ; 

 and on Fly river, New Guinea, on the 2nd of July, 1876, in extreme profusion (Signor 

 L. M. d'Albertis). Specimens in fluid are in Mus. Civ. di Stor. Nat. di Genova, and in 

 M'Lach. Mus., and some remnants of a pinned 6 example in Brit. Mus. 



The ' Annali ' above cited, after my diagnosis of the species, quote a passage from Signor 

 d'Albertis's travels relating to this insect, whose purport may be thus freely summarized. 

 On the 2nd of July, 1876, a few hours before sunset, wo witnessed a strange and magni- 

 ficent sight produced by an abundance of a species of Mayfly, actively pursued by the 

 following birds: — Calornis metalUca, Artamus cucopifgkdis, a Graculus, a Eurystomtis, 

 and the commonest Whiteheaded Osprey, HaUastur (jirrenera. Simultaneously the 

 insects were being preyed upon by thousands of fishes, who rushed up to seize them 

 whenever they touched the water with their delicate wiugs. But so profuse was the 

 abundance of the flies, that the ravages of all their destroyers caused no appreciable 

 diminution in their numbers. Mile after mile, from bank to bank, the river seemed 

 covered with them, when all at once, as if by signal, the whole of them rose up 

 confusedly, flying aloft in a thousand different directions, producing an eff'ect in the air 

 like that of a heavy fall of snow ; then they descended again, and the snow seemed to 

 cover the river with a white layer. The males very largely outnumbered the females. 



Subgenus 



? Palingenia atrostoma, Weber. 



Ephemera atrostoma, Weber, Obs. Ent. 99 (1801). 



Palingenia atrostoma, Pict., Hist. Nat. Nevroiit. ii. Epliem. 1.^)7 (1843-5) ; Walk., List of Neuropt. 

 Ins. in Brit. Mus. part iii. 550 (1853). 



1 He.ru genia atrostoma, Etn., Trans. Ent. Soc. London (1871), G5. 



Wings fuscous. Body yellow; mouth black; dorsum of abdomen fuscous ; setce fuscous. 



Hah. Brazil. In 1871 I ranked this species conjecturally with Hexagenia. At that 

 time the genus Palingenia was not positively known to be represented in America ; but 

 now that a species of this group (represented by the nymph in the Museum of Com- 

 parative Zoology, Cambridge (Mass.), figured in PL XXV. of the present work) has 

 been ascertained to occur in the Amazons, Weber's description of the species atrostoma 

 as " Gigas in hoc geuere ; thorax marginatus canaliculatusque ; cauda biscta, setis 

 longissimis," taken in connexion with the (iolours of the wings and body, lends proba- 

 bility to the supposition of its being a Palingenia. Pictet was disposed to refer it to 

 what is now known as Gampsurus. The furrows of the thorax are adverse to its being 

 considered to be a Euthi/plocia. 



Subsection B of Section 1. — Wing-neuration scanty ; anal nervure (8) of the fore wing 

 curved ; axillary nervures either rudimentary or obsolete, or represented by a branch 

 of the anal nervure (8) that meets the terminal margin ; wing-membrane transparent ; 



