158 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.58. 



apex of the first vein. Costal index about 1.9; fourth vein index 

 about 1.3 ; 5x index about 1 ; 4c index about 0.8. First posterior cell 

 slightly narrowed at its apex. 



Length, 2.5 mm. 



Type.— Male, Cat. No. 22725, U.S.N.M., from Trinidad River, 

 Panama (A. Busck). 



Female. — Proboscis, lower part of pleurae, and second and third 

 coxae shining blackish brown. Otherwise as above. 



Allotype. — Same locality as type. 



Paratypes. — Thirty-one specimens taken with the type and allo- 

 type. Three of these were bred from " white toadstool." This series 

 was taken with the large series of Z dispar referred to above. Some 

 of the paratypes are distinctly paler in color than the type, appar- 

 ently having been pinned when younger. In these specimens the 

 wing spots are smaller or even absent, and the mesonotum, scutellum, 

 and abdomen are brownish or yellowish. 



The species is named for Prof. J. M. Aldrich, to whom I am in- 

 debted for several of the references to the genus and for other favors. 



(SPHYRNOCEPS) ZYGOTHRICA (?) BRUNNEA deMeijere. 



Sphyrnoceps hrunnea deMeijere, Tijds. v. Ent., vol. 58, 1915, suppl., p. 58. 



Eyes rounded in both sexes. Thorax, dark brown above, pale yel- 

 low below. Wings clear. 



Described from the island of Simalu, off Sumatra. 



NOTE. 



Since the foregoing was written I have examined a series of 

 specimens taken on a decaying agaric on rotten log, at Emperor Val- 

 ley, Port of Spain, Trinidad, West Indies; January, 1913, by Prof. 

 Roland Thaxter. This series, which is preserved in alcohol, in- 

 cludes numerous specimens of Zygothrica dispar and of Z. aldrichii. 

 An examination of the specimens of Z. dispar and reexamination of 

 some of the United States National Museum material shows that 

 the males of this species are quite variable in the structure of the 

 head. A few of them have rounded eyes and three orbital bristles, 

 exactly as in the females. There is a continuous series connecting 

 these forms with those that have very long pointed eyes and no second 

 orbital bristle. This observation serves to strengthen the view that 

 Z. aldrichii and the genus Sphyrnoceps should be placed in the same 

 genus as Z. dispar. 



