no Memoirs of the Indian Museum. [Vol. Ill, 



second; arista plumose^ on the upper side with longer hairs; face flat, the epistome 

 not prominent. 



Thoracic chaetotaxy reduced; no prst. and no dc, the prsc. more separated 

 tlian in the other genera ; 2 mpl. ; pt. much weaker than in the preceding genera. 

 Scutellum as flat as the dorsum of thorax, with four bristles. 



Abdomen flat, narrowed at the base, with six distinct segments, the last bristly 

 on the sides ; male genitalia not prominent ; ovipositor flattened , a little longer than 

 the two last abdominal segments. Front femora with a row of bristles beneath; 

 middle tibiae with a single spur ; hind tibiae with a row of hairs on the outside. 



Wings proportionally long and narrow, blackish with hyaline indentations and 

 spots; a distinct costal bristle ; veins straight, the 3rd and 4th parallel; the small 

 cross vein beyond the middle of the discal cell ; hind cross-vein short and perpendi- 

 cular; anal cell drawn out into a point, as long as the second basal cell, the point 

 broad. 



Type: Ptilona brevicornis , Wulp. 



This genus was originally erected by Van der Wulp (Tijdschr. v. Bntom., xxiii, 

 183, 1880), for some different apecies, of which the first is to be considered as the 

 type; subsequently the genus has been restricted by Osten-Sacken and Prof. Meijere, 

 the other species being referred to Rioxa. Through the kindness of Prof. Meijere, 

 who has examined the type of Pt. brevicornis at Amsterdam, I can say that the dc. 

 are not present, an important circumstance which has been overlooked by other 

 authors even by Enderlein (Zool. Jahrbuch., xxxi, 415). 



18. Ptilona nigriventris, n. sp. c? , 9 . 

 (PI. viii, fig. 20.) 



Very like brevicornis ^ but distinguished by having the hyaline indentation of the 

 third posterior cell divided into two spots, and the abdomen wholly black, except at 

 the base. Length 6-7 mm. 



The present species differs from Wulp' s description, besides the wing-pattern, in 

 having the lower or. curved forward not behind as in Wulp' s figure; the head is less 

 narrowed. The frons is a little concave, at the vertex whitish yellow and shining ; 

 on the sides it has a shining small stripe, which ends anteriorly in a tubercle on 

 which is inserted the single superior or. ; all the bristles are black ; occiput below 

 with black hairs. Palpi with black bristles. 



All the bristles of the thorax and the sc. also black ; the pubescence on the 

 dorsum and pleura black ; inferior part of mesopleura and pteropleura and superior 

 part of sternopleura black. Squamulae with dark hairs. 



Abdomen black, with the two first segments dark yellow; the hairs black; ovi- 

 positor black. Bristles and hairs on the legs all black. 



A consideration of the wide distribution of brevicornis , which ranges from Java 

 to the Philippine Islands, may perhaps be taken as evidence that P. nigriventris is 

 oi]]y an Indian form of that species ; but the distinctions seem to me sufficient. In 



