NO. 6 GRASSHOPPER ABDOMEN SNODGRASS 63 



The phallic organs of the Acrididae consist of a complex of struc- 

 tures arising from the floor of the genital chamber (fig. 24 A), and 

 ordinarily they are entirely enclosed within the genital chamber. 

 Posteriorly is the intromittent organ, or aedeagus (Aed) , which has 

 an upright position and is lodged in the pocket beneath the pallial 

 hood. In front of the aedeagus is a broad sloping area of the genital 

 chamber floor, often rounded and elevated, which rises posteriorly 

 in a prominent transverse basal fold (bf) that more or less conceals 

 the proximal part of the aedeagus. In the anterior pocket of the 

 genital chamber, seated transversely on the floor of the latter beneath 

 the venter of the tenth abdominal segment, is the epiphallus (Epph), 

 a large irregular sclerite characteristic of the Acrididae. 



The aedeagus (fig. 24 A, Aed) is a complex organ, somewhat 

 variable in the relative size and shape of its parts in different genera, 

 but having a constant basic structure that can be recognized in all 

 cases without difficulty. It consists essentially of an irregular dorsal 

 lobe (dl), and of a simple ventral lobe (z/l). Because of the vertical 

 position of the organ the dorsal lobe is anterior and the ventral lobe 

 posterior. These two principal parts of the acridid aedeagus are 

 apparently to be identified with corresponding lobes of the intromit- 

 tent organ in Tettigoniidae ; the ventral lobe is the most constant 

 structural feature of the diverse copulatory apparatus of Blattidae, 

 Mantidae, Tettigoniidae, and Gryllidae, since it always has the form 

 of a soft or partly sclerotized flap projecting below the external 

 genital opening. In the Acrididae the outer genital aperture, or phallo- 

 trcuie, is a vertical cleft in the entire length of the ventral (posterior) 

 surface of the dorsal lobe of the aedeagus (figs. 24 C, 2>7 ^^ Phtr), 

 but the ventral lobe (vl) projects beneath its proximal part, and thus 

 has the same relation to the genital opening as has the corresponding 

 lobe in the families above mentioned. 



The dorsal lobe of the aedeagus is divided typically into a broad 

 proximal part (fig. 24 B, m) , and a smaller, usually cylindrical distal 

 part (r), from the end of which there project two pairs of apical 

 processes (n, p). In some forms, however, the distal part of the 

 aedeagus is small or absent, and in such cases the apical processes are 

 generally relatively large (fig. 31 C) and are carried directly by the 

 proximal part (m). The distal part of the dorsal lobe is best developed 

 in the Cyrtacanthacrinae (fig. 37 A). Both the distal and the proximal 

 parts of the dorsal lobe are deeply cleft posteriorly by the phallotreme 

 (figs. 24 C, 37 C, Phtr), which invades the extremity of the organ 

 between the apical processes, and extends proximally to the base of 

 the ventral lobe. 



