66 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94 



endophallus as a broad apodeme (w) for muscle attachments. The 

 endophalHc plates are the " endoparameres " of Walker (1922), who 

 believes that they are representatives of external or variously invagi- 

 nated plates or processes (" parameres ") of other Orthoptera. By 

 comparison w^ith Tettigoniidae it does appear probable that the endo- 

 phallus of Acrididae is produced as an invagination of the posterior 

 surface of the dorsal lobe of the aedeagus. 



The cavity of the endophallus is mostly a narrow vertical space 

 between the lateral endophallic plates, but its posterior membranous 

 part, somewhat expanded behind the oblique posterior margins of 

 the lateral plates, forms a distinct section of the lumen, and may be 

 designated the spennatophore sac (fig. 24 C, sps). The ejaculatory 

 duct (Dej) opens into the ventral part of the spermatophore sac 

 through a terminal ejaculatory sac (ejs). The aperture between the 

 two sacs is the true gonopore. Dorsally the spermatophore sac com- 

 municates with the phallotreme cleft in the dorsal lobe of the aedeagus 

 through the meatus at the base of the latter. From the lower anterior 

 angle of each lateral endophallic plate a long process {y) projects 

 backward in the membranous connecting wall between the spermato- 

 phore sac and the ejaculatory sac. The two processes thus closely 

 embrace the gonopore (fig. 29 E, F, fig. 33 C), and, as will be shown 

 later, by the action of the endophallic muscles they regulate the open- 

 ing and closing of the gonopore. Lateral vesicles of the ejaculatory 

 sac, such as are present in most other Orthoptera, are absent in the 

 Acrididae. 



The curious sclerite known as the epiphallus is a very prominent 

 feature of the acridid genitalia. It is situated on the floor of the 

 anterior pocket of the genital chamber beneath the venter of the 

 tenth and eleventh segments (fig. 24 A, Epph), and is separated from 

 the aedeagus by the sloping surface that culminates posteriorly in the 

 hoodlike fold (&/) covering the base of the aedeagus. The morpho- 

 logical nature of the epiphallus is doubtful, since the sclerite cannot 

 be satisfactorily identified with any part of the phallic structure 

 in other insects. The plate is termed the " pseudosternite " by 

 Walker (1922) and by Ford (1923). It has muscular connections 

 both with the ninth sternum and with the zygoma of the aedeagal 

 apodemes. In form the epiphallus is an irregular transverse sclerite 

 (fig. 31 B) consisting of two expanded lateral lobes {h, h) connected 

 by a narrow median bridge {i). Anteriorly the lateral lobes bear a 

 pair of hooklike processes (/) directed forward, and posteriorly each 

 is produced upward in a large thick irregular transverse process {k). 

 Closely associated with the epiphallus laterally are two small oval 



