310 NEUROPTERA. 
An American genus, the number of whose species has yet to be definitely ascertained. 
All members of the present fauna are to be referred to one variable form. 
1. Perithemis domitia. 
Libellula domitia, Drury, Ill. Nat. Hist. ii. t. 45. fig. 4 (g in colours) and Index (1773) *; ibid. 
Westwood’s edit. ii. p. 83, t. 45. fig. 4 (id.) (1837)?; Hagen, Syn. Neur. N. Amer. pp. 185, 319 
(1861)*; Proc. Bost. Soc. Nat. Hist. xviii. pp. 82, 93 (1875)*; Calvert, Proc. Calif. 
Acad. Sci. (3), Zool. i. p. 402 (1899)°; Ris, Hamburg. Magalh. Sammelr., Odon. p. 30 
(1904) °. 
The males and females having their wings quite dissimilarly coloured, it is often a 
matter of difficulty to correlate the sexes of the various forms under which this species 
appears. Some aid in this attempt is furnished by the venation, whence it follows 
that a given peculiarity of venation possessed by both sexes is a more important 
diagnostic character than the markings of the wings exhibited by the female alone. 
On this basis it is possible to distinguish several forms of this species, connected 
with each other by intermediates (and hence not entitled to specific rank), but whose 
geographical distribution is not yet sufficiently known to enable them to be regarded 
as subspecies in the sense of the Code of the American Ornithologists’ Union. The 
forms found in Mexico and Central America are :— 
A. Hind wings with the discoidal triangle 2- or more-celled, no single cell 
reaching across the entire width of the post-triangular field, usually 
6 antecubitals ; front wings with discoidal and internal triangles two- 
or more-celled, and with 3 (or 2 increasing to 3 at the level of 
origin of subnodal sector) post-triangular rows ; wings of the female 
banded with brown, the distal band having its proximal edge at the 
nodus or more remote . . . . . . . «© © © «© «© « © « . Form intensa. 
AA. Hind wings with the discoidal triangle free, one or more single cells 
reaching across the entire width of the post-triangular field, usually 5 
antecubitals ; front wings with the discoidal triangle free, internal 
triangle one- or more-celled, two post-triangular rows increasing to 
three rows at the level of origin of subnodal sector, or at the level of 
the nodus or beyond, which three rows continue to, or almost to, 
the wing-margin. 
[B. Wings of the female yellow for their entire width from base to 
nodus, and in only the costal space from nodus to stigma . . . . Form domitia type ?] 
BB. Wings of the female yellowish or yellowish-brown in the costal 
space from base almost to stigma, in the subcostal space from base 
to nodus or slightly beyond, in the submedian space and for one or 
two cells between the sectors of the arculus; hind wings sometimes 
with a small brown dot at extreme apex .. . er . Form iris. 
BBB. Wings of the female with two transverse brown or ‘blackish bands, 
the distal band having its proximal edge several cells proximal to 
