414 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 113 
are deposited in the Los Angeles County museum, the California 
Academy of Sciences, the U.S. National Museum, and in collections 
of the authors. The illustrations were made by Mrs. Patricia J. 
Hogue, of Arlington, Virginia. 
Subgenus Stridulivelia Hungerford 
Velia (Stridulivelia) Hungerford, 1929, Journ. Kansas Ent. Soc., vol. 2, p. 55. 
The members of this subgenus possess certain structures that clearly 
set them apart as a natural group from all other members of the genus 
Velia. These distinguishing features are: (1) general habitus; (2) 
intersegmental furrows between abdominal segments; and (3) vertical 
median furrows (one on each side) of abdominal pleurites II-III, 
II-IV, or II-V. ‘These pleural abdominal sulci, both intersegmental 
and segmental, are present in both sexes. The presence or absence of 
the stridulatory organs and the number of abdominal pleurites bearing 
a median vertical furrow separate the members of Stridulivelia into 
“oroups”’ of species. 
The sound-producing mechanism consists of (1) a small subbasal 
filelike area on the inner face of each hind femur (pl. 1,¢) and (2) 
a closely set row of small pegs near the upper margin of the inferior 
side of each connexivum (pl. 1,b). The soniferous structures, adapted 
for rasping performance, are paired (one of each on each side of the 
body) (pl. 1,b,c) and are similarly developed in both sexes. 
In one of the South American members of the subgenus, Velia alia 
Drake (1957), from British and French Guianas, the parts of each 
pair of stridulating organs are exactly reversed in their positions. 
In alia, the connexivum is equipped with a long narrow, finely or mi- 
nutely cross-striated rodlike file and the hind femur with a small elon- 
gate-oval patch of tiny pegs. Furthermore, the latter species differs 
from all described forms in having a prominent spiniform process at 
each humeral angle. ‘The humeral hornlike processes and sound organs 
are the same in both sexes. The other South American members of 
the subgenus have the stridulating structures placed and arranged as 
in the Antillean V. tersa (pl. 1). In either type of stridulatory arrange- 
ment, sound is effected by the confrication of the stridulating structure 
of the hind femur with that of the connexivum on the same side of the 
body. The abdomen, especially the connexivum, serves as a resonator. 
All members of the subgenus so far described from South America are 
equipped with the rasping structures. 
The metasternal omphalium (pl. 2, a) is large and distinctly gibbose ; 
its hind margin is obtusely angulately rounded. The opening of the 
metathoracie scent glands is just beneath the median subangulate 
