162 MAJOR F. C. FRASER ON 



Aeshninae, Gomphinae, Libellaginde (except for a specimen of 

 Micromerus lineatus) are all unrepresented. 



1. PoTOMARCHA OBSCURA Rami). 



A female from Na Kram, which is brightly coloured as in 

 the wet season forms. 



2. Orthetrum sabina Drury. 



2 males and a female from Ban Siew. 



3. Orthetrum pruixosum Burnr. 



1 female from Bang Pak Tung, and 2 males from Na Kram. 

 4. Crocorthetrum smithi, sp. nov. 



A single male from diet Ton, Jan. 1, 1920. 



Length of hindwing 34 mm. Abdomen 28 mm. 



Head comparatively small ; eyes moderately contiguous ; occi- 

 pital plate large ; frons flattened in front and shaped as two horse- 

 shoe shaped areas separated by the suture which is deep. The eyes 

 are blood red, paler below, the face dark ochreous and blood red on 

 the frons and above, as is also the vesicle. Occiput dark reddish 

 brown. 



Prothorax with a very large posterior lobe which is fringed 

 with long hairs. Reddish brown. 



Thorax moderately robust, almost naked save on the front of 

 dorsum, colour a golden, reddish brown. 



Legs reddish, distal ends of femora and tibiae black ; hind 

 femora with a row of short, robust, moderately closely set and 

 gradually lengthening spines ; mid femora with fewer but longer 

 spines. Tarsal claws robust, situated nearest the apex. 



Abdomen dilated dorso-ventrally at the base, triquetral, taper- 

 ing from base to apex, bright crimson without markings. 



Anal appendages reddish, the superior as long as the 9th 

 abdominal segment, inferior shorter, excavate above at the base and 

 with two minute points at the end, the rudiments of a fissure. 



Genital organs ; lamina depressed, fringed with stiff, short, 

 golden hairs. Its outer surface furnished with two long tufts of hair 

 the ends of which are a little recurved ; internal hamules blunt, 

 strongly curved, converging hooks; external hamules small, flattened 

 and not over lapping the lobe; lobe subquadrate, small. 



JOURN. NAT. HIST. SOC. SIAM. 



