SOME SIAMESE TAB AN ID AE. 443 



triangles ; anterior brancli of third longitudinal vein in wing with a well marked 

 recurrent appendix. 



Head : Front and subcallus olive-buff pollinose, upper half of front appearing darker 

 when seen from certain angles (looking almost mummy-brown when viewed at a 

 low angle in an antero-posterior direction) ; face, jowls and occiput pale smoke-grey 

 polUnose, clothed with whitish hair, upper extremities of sides of face faintl\' 

 suffused with sepia and clothed with dusky or blackish hair, hind margin of upper 

 part of posterior orbits with an inconspicuous fringe of very short black hair, front 

 in 5 clothed with minute dusky hairs ; front in $ narrow, diminishing in width 

 from above downw^ards, and about eight or between eight and nine times as long as its 

 breadth between lower inner angles of eyes, ocellar tubercle wanting ; frontal callus 

 (see fig. 4a), dark chestnut-brown, vertically elongate (roughly elliptical — its base 

 just above lower inner angles of eyes), exhibiting a median impressed line, and 

 continued above into a linear prolongation ; palpi in $ drab-coloured, proximal 

 segment clothed with whitish hair, distal segment narrow and elongate, blunt at 

 tip and but little thicker at base, clothed on outer surface with minute, appressed 

 black hairs ; antennae, russet, first and second segments clothed with minute black 

 hairs (with yellowish hairs on lower margin of their distal extremities), first segment 

 somewhat gre3'ish polhnose above, strongly swollen distally, its upper distal angle 

 produced and partly embracing second segment, upper distal angle of latter con- 

 siderably elongate, expanded portion of third segment in $ of considerable depth 

 at base, not elongate and having a prominent, blunt angle half-way along its upper 

 margin, annulate portion of third segment (dark chestnut-brown in case of type) 

 about one-fourth shorter than expanded portion. Thorax : Dorsum, including 

 scutellum, thinly, pleurae and pectus densely smoke-grey pollinose ; dorsum, 

 including scutellum, clothed with semi-erect black hair, mixed with fine, appressed 

 or recumbent, ochreous or yellowish hair, a tuft of whitish hair also present above 

 base of each wing and on post-alar calli ; swelling occupying depression at each end 

 of transverse suture, as well as post-alar calli in part and a small area on each side 

 behind and above tuft of whitish hair above base of wing clothed with black hair ; 

 pleurae and pectus clothed with whitish hair. Abdomen : tergites of second to fifth 

 segments inclusive each with a light buff, median triangle resting on its hind margin, 

 the triangle in each case being formed by a patch of appressed, glistening straw- 

 yellow hairs clothing a light buff pollinose triangular area ; in case of holotype and 

 paratype, triangle on second segment is isosceles, and its apex extends somewhat 

 beyond middle of length of segment, while remaining triangles are equilateral and, 

 except in case of triangle on fifth tergite, do not extend as far as middle of their 

 respective segments ; lateral extremities of first (visible) tergite palhd neutral grey 

 pollinose, ground colour of lateral extremities, or at least posterior angles of following 

 five tergites ochraceous-tawny ; lateral extremities of first (visible) and three following 

 tergites clothed with whitish or silvery-white hair ; a small, triangular patch of ap- 

 pressed, glistening straw-yellow hairs on hind margin of first (visible) tergite in 

 middle line, sixth tergite with a more or less distinct, median triangular patch of 

 similar hair, interspersed with minute black hairs, the patch resting on hind margin 

 and showing individual variation in size, being sometimes very small, in other cases 

 considerably larger, so that its apex almost reaches hind margin of preceding 

 segment ; owing to absence of a light buff, pollinose ground beneath the median 

 patches of appressed straw-yellow hairs on the first and sixth tergites, these patches 

 are somewhat inconspicuous and do not appear as clearly defined triangles, con- 

 trasting sharply with surrovmding area, as in the case of the median markings on the 

 four intervening segments ; fourth and fifth tergites with a few glistening straw- 

 yellow hairs on their posterior angles ; lateral extremities of last three, and hind 

 margins of last two tergites clothed with black hair of moderate length ; dorsum, 

 except as stated, clothed with minute, appressed black hairs ; venter russet, hind 

 margins (or at least their lateral extremities) of second to fifth sternites, inclusive, 



(5296) 2 K 



