10 
alternation of generations has been established. The small wingless 
form, originally described by Riley as tritici, is the vernal generation, 
and consists of both sexes. The large winged form, described as grande, 
is the summer generation, and consists entirely of females. The species 
is widespread, occurring through the middle belt of country from the 
Atlantic to the Pacific, and has been reared only from wheat stalks. 
The name tritici Riley falls on account of its prececnpa io: ich 
Dr. Riley was familiar with Fitch’s name, but reviv: for the present 
species, thinking with Walsh that tritici Fitch was 
Harris. Riley’s name, however, even in that event, wild ve been 
rejected under the law of “once a synonym always 2 synon,\ The 
dimorphism in this species is fortunate, since it cuales us % retain 
Fic. 1.—Isosoma grande Riley. 
Riley’s name for the summer form as the specific name. The species 
must, therefore, be known as follows: 
Isosoma grande Riley. 
Form grande—winged summer generation. 
Form minutum' (proposed in place of trifici)=wingless spring and winter 
generation. 
Isosoma californicum n. sp. 
Female.—Length, 5 mm.; expanse, 8mm. Head and thorax rather 
coarsely EE ee aaa petiole disthinets but short and stout; 
abdominal segments 5 to 8 shorter than 4, 2 2 and 5 subequal, 3 and 4 
subequal; mesoscutellum pointed at tip, axille nearly meeting; meta- 
notum with a straight central longitudinal groove which is regularly 
concave from side to side and slightly emarginate at borders; each 
side of the groove the metanotum is coarsely umbilicate-punctate; hind 
cox plainly granulate above. Antennz rather short and stout joints 
‘For a good Aeae be fottn minutum, see Ann. Rept. Dept. ao , 1881-82, mine xii, 
fig. 3 
