110 Rey. A. E. Eaton’s Monograph 
Centroptilum stenopteryx, 0. sp. 
(Ala postica et forceps, Pl. V. fig. 15, 15a.) 
Subimago, v. s. s. ¢. Ale vix fumate. Thorax 
ochraceus, pedibus testaceis, tarsis pallidis. 
Imago, v.s.s. 6 uxori simillimus, corpore furfuroso, 
setisalbis. [Oculi turbinati olim rufescentes ? ]. 
Long. corp. ¢ 4, 2 45; al. d 4, 2 5°; set. d @ 
5-6 mm. 
Hab.—Carinthia (Zeller’s MS.). 
Genus BaAgEtis. 
(Ala antica, Pl. II. fig. 9.) 
Ephemera, p., Lin. 1746; Baetis, Leach, 1815; Cloe, 
p., Burm. 1839; Brachyphlebia, Westw. 1840; Cloeon, 
p., Walk. 1853. 
Nympha agilis, laminis branchialibus simplicibus, in- 
tegris, ovatis vel obovatis, septem utrinque.  Palpi 
maxillares biarticulati, articulis longitudine subeequalibus ; 
superiores teretes ; inferiores proximis articulorum sub- 
cylindricis, apicalibus depressis et spathulatis atque lat- 
eraliter incisis. Dimidia labu acuta, subulata, maxillis 
angustiora. 
Subimago inter quiem Cloconi vel Centroptilo simulat. 
Imago. Oculi maris partiti, superioribus dimidiorum 
sub-turbinatis. Ales quatuor; posteriores minime, ob- 
long, costi unidentati, atque tribus vel duobus nervo- 
rum longitudinalium, quorum secundus vel simplex vel 
divisus sit. Seta due (B. ferrugineus tamen tertiam 
mediam brevissimam habet). Forcipis artus quadri- 
articulati, penultimis articulorum plerumque longissimis. 
Femina ovivalvuli caret; nisi fugax sit. 
The species mostly inhabit rivers and streamlets. 
They appear principally in spring and early in the au- 
tumn; but the exact period depends upon climate. 
Monstrous specimens seem to be more frequently met 
with in the autumn than in the spring; they throw 
much light upon the morphology of insects in general. 
