248 
NORTH AMERICAN MYRMOSIDAE 
additional to, that given by Fox in his Monograph d The color 
nomenclature is, for the most part, that of Mr. Robert Ridgway.^ 
A Key to the Genera of Myrmosidae known to occur in 
America north of AIexico 
1 . Ocelli of the female present; hypopygium of the male unarmed; marginal 
cell of the fore-wings long, reaching nearly to the apex of the wing 
(figure 2 ); posterior coxae each with a prominent lamina on its upper 
surface at base Myrmosa Latreille 
Ocelli of the female absent; hypopygium of the male armed with an acu- 
leus; marginal cell extending but a short distance beyond the stigma, or 
ending in it (figure 5) (2) 
2. Middle tibiae with two apical spurs; in the males the first abdominal seg- 
ment consisting of a basal petiolar portion and an apical more or less 
gibbous portion, the two separated by a transverse suture; mesosternum 
of the males without a caudal lamella on each side of the middle projecting 
over the base of the coxa (3 ) 
Middle tibiae with one apical spur; basal abdominal segment not consisting 
of two parts; mesosternum with a prominent caudal lamella on each side 
of the middle encasing the base of the coxa. (Males.) . . Brachycistis Fox 
3. Abdomen petiolate; posterior coxae simple (4) 
Abdomen sessile; posterior co.xae each with a prominent lamina on its 
upper surface at base. (Females) Brachycistis Fox (?) 
4. Front wings with the transverse part of M 2 wanting; the cell Es about one- 
half the size of the cell R -t- 1 st Ri; Rs present and not far apicad of the 
radial cross-vein (figure 3); the first abdominal segment of the female 
greatly widened before the apex Typhoctes Ashmead 
Front wings with M 2 complete; the cell Rs joined with R 4 , the vein R 4 far 
apicad of the radial cross-vein, the two united cells thus nearly as long as 
the cell R + 1 st Ri, or in some cases both cells R 4 and R 5 present and 
distinct (figure 4); petiole of the females filiform throughout. 
Chyphotes Blake 
MYRMOSA Latreille 
Type; Mutilla nigra Rossi, =4/. melanoceplmla Fabriciiis. 
Myrmosa was originally described without included species, and 
Mutilla nigra was placed in it by Latreille in 1802. 
1 The North American MutilUdae. By William J. Fox. Transactions of 
the American Entomological Society. 1899. 25 : 219 to 292. 
2 Color Standards and Color Nomenclature. By Robert Ridgway, Washing- 
ton, D. C., published by the Author, 1912. 3 p. 1., iv, 44 p., 53 col. pi., 22 cm. 
