312 NEUROPTERA. 
Taken in April and May in Arizona, from June to November in the Mexican localities. 
This is the most densely veined form of Perithemis so far known in North America. 
It is the only form yet found west of the Sierra Madre and north of the Isthmus of 
Tehuantepec, but it also occurs east thereof at Fuente and in Yucatan, facts yet to be 
explained. From notes and photographs which Dr. Ris has kindly sent me, it appears 
that many of the Perithemis which he collected at San Isidro, near Buenos Aires, 
in Argentina ®, have almost the identical venation of intensa, and the wings of the 
females tend toward traces of transverse bands located as in intensa. All of these 
he regards as the form described by de Selys as tcteroptera*. A question for future 
determination is whether intensa and icteroptera have a continuous geographical 
distribution or are illustrations of independent acquisition of similar characters 
(convergence). At San Isidro were also taken two females of form mooma, vide postea. 
Intermediates between forms intensa and tenera. 
The banding of the wings of the females of these two forms is very similar, so that the differences are mainly 
in venation. The following individuals present intermediate conditions of venation :— 
A female from Florence, Ariz. (Biederman, A. N.S.), abd. 15°5, hind wing 21 mm., bas the wing-bands 
approximately as in Tab. VI. fig. 11, except that the distal band is narrower, 2-3 mm.; front wings with 
discoidal triangle 2-celled, internal triangle free, three post-triangular cells, then two rows increasing to 
three rows near level of origin of subnodal sector, decreasing to two cells (right) or rows (left) near level 
of nodus, again increasing to three rows, again decreasing to two cells (right) or rows (left), terminating 
in three rows (four cells, right) at the margin ; hind wings with triangle 2-celled (right) or free (left), a 
single cell reaching across the whole width of the post-triangular field on the right but not on the left, 
6 antecubitals. 
A female from Catalina Mts., Ariz. (Oslar, coll. Wilmsn.), of the same size, similar wing-banding, distal band 
narrower, 1°5—2 mm., has front wings with discoidal triangle 2-celled, internal triangle free, two post- 
triangular rows from triangle out to beyond nodus-level (interrupted by three rows for two cells before 
the nodus on left side only); both hind wings with triangle 2-celled, a single cell reaching across the 
whole width of the post-triangular field on the right side only, 6 antecubitals. 
A female from Las Bocas, Durango (Batty, A. M. N. H.), abd. 14, hind wing 19 mm., wing-markings 
approximately as in Tab. VI. fig. 14, has front wings with ail triangles free, two post-triangular rows to 
beyond nodus-level (interrupted by three rows for two cells before the nodus on left side only); both 
hind wings with triangles 2-celled, a single cell reaching across the whole width of the post-triangular 
field on the left side only, 6 antecubitals. 
Less strongly-marked and mostly asymmetrical deviations toward tenera venation are displayed by a number of 
the individuals of both sexes listed under intensa above (cf. Calvert’, tables p. 405). 
[b. Form domitia. 
Perithemis domitia, Kirby, Trans. Zool. Soc. Lond. xii. p. 325 (1889) °; Ann. & Mag. Nat. Hist. 
(6) iv. p. 282 (1889) *°; ? Scudder, Proc. Bost. Soc. Nat. Hist. x. p. 198 (1866) ™. 
? Libellula domitia, Burm. Handb. Ent. ii. p. 855 (1839); Calv. Trans. Amer. Ent. Soc. xxv. 
p. 75 (1898) **. 
Libellula metella, Selys in Sagra’s Hist. Cuba, Ins. p. 451 (1857) ™. 
As has been previously pointed out’*, the figure of domitia given by Drury’ is asymmetrical in the cells of the 
triangles and, even if it accurately represents the specimen from which it was made, cannot possess any 
* In Sagra’s Hist. Cuba, Ins. p. 401 (1857). 
