484. 



BAETIS DISPAR. 



The dissimilar May-fly. 



Order Neuroptera. Fam. Ephemeridae. 



Type of the Genus, Baetis dispar Curt. 



Baetis Leach, Sam., Curt. — Ephemera Linn., Fab. 



Antennce inserted in 2 cavities in front of the face (1* a), short 

 setiform and triarticulate, basal joint veiy short and cup-shaped, 

 2nd ovate, 3rd forming a coriaceous seta (1). 

 Trophi none ? 



Head transverse, hemispherical : eyes large, meeting on the crown 

 of the head in the male (1*, front view), remote in the female : 

 ocelU large, 3 in triangle, placed before the eyes, the lateral ones 

 elevated (o) : clypeus very large, coriaceous, somewhat semicircular, 

 carinated down the middle and very deeply notched at the centre 

 (c). Thorax ovate. Abdomen rather short and termifiated by 2 

 seta (6 and 7 f) ; attenuated in the male with two 4-jointed appen- 

 dages (7 c, being a portion of the underside) ; the female fur^iished 

 with a single process ; (6 the apex in profile). Wings 4, mostly 

 thickly reticulated, superior long and narroio ; inferior small and 

 subovate. Legs, anterior inserted close to the head, very long in the 

 male (8), the others short : thighs compressed : tibiae simple ; tarsi 

 5-jointed, anterior much longer than the tibia in the male (8), the 

 basal joint much shorter than the Ind or 3rd, which are very long, 

 4th longer than the Isf, 5th about the same length, the joints nearly 

 of equal length in the female, the 4th a Utile the shortest ; the other 

 tarsi are rather short and alike, the terminal joint being as long as 

 the basal one, the 4th minute (f tibia and tarsus of hind leg) : chvws, 

 one horny curved and acute, the other an ovate and fieshy lobe like a 

 pulvillus (c, terminal joint of tarsus and claws). 



Obs. The dissections are from B. dispar. 



Metamorphosis quadruple. 



Larvae and Pupae with 6 feet, 12 external lobes and 3 broad short tails. 

 Roesel (v. 2, tab. 12, f 3 and 4) : Pseud-imago similar to the j)er- 

 fect insect. 



Dispar Curt. Guide, Gen. 735. 2. 



Pale castaneous, eyes and disc of thorax sometimes much darker 

 in the male ; segments of the abdomen with the margins brown, 

 filaments more than twice as long as the insect ; tibiae, except- 

 ing the anterior pair, ochreous towards the apex, tarsi fuscous : 

 wings transparent, superior pale yellow at the base in the male, 

 as well as the costal margin, which is pale brown towards the 

 apex, nervures of the same colour. 



In the Cabinets of Mr. Dale and the Author. 



The habits and oeconomy of the Baetes are similar to the 

 Ephemerae, from which they are distinguished by having only 



