116 AMERICAN ENTOMOLOGY. 



The lower left figures of the plate represent the species in two 

 positions. The line shows the natural length. 



SPHYKACEPHALA. Plate LII. 



Essential character. Head extended each side in a process 

 which is oculiferous at tip ; antennae inserted on the front, third 

 joint rounded, compressed, setigerous at tip. 



Natural character. — Head subtriangular ; eyes pedunculated, 

 peduncles very short, robust; stemmata approximate ; Antennae 

 distant, robust, short, nearly parallel to the peduncles, three- 

 jointed; first joint very short, almost concealed; second joint 

 obconic, ciliated at tip ; third joint orbicular, setigerous at tip ; 

 proboscis bilabiated ; palpi elevated, conic ; metathorax with a 

 conic spine each side beneath the wings ; scutel two-spined ; 

 poisers naked ; wings incumbent ; feet moderate ; anterior thighs 

 dilated ; anterior tibiae a little arcuated. 



Obs. Two genera of dipterous insects have already been con- 

 stituted, in which the eyes are pedunculated, or situated at the 

 extremity of elongated, immovable processes of the head : these 

 are Diopsis of Linneus, and Achias of Fabricius. The present 

 genus differs from the former, however, in not having the an- 

 tennae situated on the peduncles of the eyes, but on the front, as 

 in Achias. It agrees with the former in the terminal origin of 

 the seta of the antennas, and in the rotundity of the third joint 

 of those organs, as well as in the armature of the scutel and late- 

 ral part of the trunk. In the little known genus Achias, we are 

 informed the terminal joint of the antennae is elongated, cylindri- 

 cal, and setigerous at base, and that its scutel is emarginate. It 

 is therefore obvious, that the genus under consideration must be 

 placed between Diopsis and Achias; and that notwithstanding 

 the brevity of the processes of the head, and the frontal origin of 

 the antennae, it appears to be more intimately allied to the pre- 

 ceding. 



Spyracephala is compounded of the words 2^*, malleus, and 

 KffaA», caput, in allusion to the form of the head. 



Sphyracephala brevicornis. — Specific character. Dusky; 

 wings bifasciate, with brown; scutel, spines, and feet yellowish. 



Diopsis brevicornis nobis, Journ. Acad. Nat. Sci. vol. i. p. 23. 



Desc. Head pale rufous, vertex and each side before the eyes 



