324 MR. W. P. KLRBY— A REVISION OF 



Perithemis Bella. (Plate LI. figs. 8 6,9 $ .) 

 Perithemis bella, Hag. MS. (?). 



Long. corp. 23 millim. ; exp. al. 34 millim. ; long. pter. 2\ millira. 



Male. — Body brown, the face, the pleura, and the sides of the base of the abdomen 

 yellowish ; thorax with a central reddish stripe, and broader oblique ones on each side 

 just before the base of the fore wings ; the first three segments are paler above (though 

 less conspicuously than below) and segments 2-4 carinated, a double row of small dark 

 spots (sometimes expanding into blotches at the base) runs down the back of the 

 abdomen, the carinated segments being marked with two on each side, and the others 

 with one only ; the dorsal and lateral carina? are black. Fore wings hyaline, more or 

 less deeply yellow at the base to beyond the triangles, on both the upper and lower 

 antenodal to the nodus, and from the nodus to the pterostigma on the first postnodal 

 space only ; pterostigma red, bounded below only by a black line, the neuration of the 

 rest of the wings is mostly brown. Hind wings wholly yellow, pterostigma as above ; 

 membranule white, narrowly edged with black. Fore wings with 7 antenodal and 4 or 5 

 postnodal nervures ; triangle rather wide, open or traversed, followed by two or three 

 rows of cells, subtriangular space consisting of three cells ; hind wings with the triangle 

 open. The abdomen is shorter and flatter than in P. domitia, Drury, and considerably 

 widened in the middle. Anal appendages about as long as the ninth segment. 



Female. — Brown, face, pleura, and base of abdomen beneath dull white rather than 

 yellowish, the thorax with the reddish markings much extended, leaving only a broad 

 yellowish stripe on each side above, the abdomen greatly constricted at the base, and 

 much flattened and widened in the middle, narrowing again towards the tip, brown, 

 blackish in the middle, with a row of long, slightly constricted spots or short yellowish 

 stripes on most of the segments on each side of the black dorsal carina; wings with 

 the nervures brown, the costa blackish, pterostigma brownish yellow, enclosed by 

 blackish nervures ; all the triangles open, that of the fore wings followed by two rows 

 of cells ; subtriangular space consisting of one cell only. Wings hyaline, lower ante- 

 nodal space yellow, spotted with brown on several of the cross nervures ; a brown spot, 

 partly bordered with yellow, covers the nodus ; hind wings hyaline at base and tip, 

 more or less of the middle of the wing yellow from the costa to the hind margin ; a 

 brown spot on the nodus, extending towards the pterostigma, and sometimes a brown 

 shade in the middle of the yellow portion of the wing. 



Hab. Santarem. 



Perithemis thais. 

 Perithemis thais, Hag. MS. 



Long. corp. 15 millim.; exp. al. 34-38 millim.; long. pter. 2-2J millim. 



Head yellow, shading into greenish on the vertex. Thorax greenish yellow, with a 

 rather broad rusty band on the middle above, and a stripe of the same colour on the 



