Revision of the Notonectide. 4] } 
Var. 2, widulata, Say. The common variety, varying from pure 
ivory-white to pale luteous or stramineous, with an undulatory 
subhorizontal blackish fascia, which is sometimes a mere thin 
line, but generally a broad band extending between the exterior 
lateral margins of the hemielytra, practically covering the base of 
the membrane, exteriorly encroaching on the corium, interiorly on 
the membrane. ‘T'he fascia never acute or furcate at its extremi- 
ties. 
This variety is, in part, N. variabilis, var. scutellaris, 
Fieb. 
Var. 3, charon, nov. The preceding variety (2) but with clouded 
hemielytra. ; 
This tendency to melanochroism increases (more par- 
ticularly in Central and South American individuals) 
until a peculiar chequered (black and luteous, or dark 
red-brown and _ brunneo-testaceous) appearance is as- 
sumed ; finally, some forms are entirely bluish-black or 
purple-brown (or both), excepting only a whitish or pale 
luteous fascia of varying width, on the clavus, this form 
being somewhat similar to N. glauca, var. marginata 
(furcata). This variety is N. widulata, var. c., Say. 
Var. 4, punctata, Fieb. The largest forms, with more prominent 
and quadrilateral eyes, bearing the same relation to ordinary wndu 
lata that insulata, var. gealu does to typical énzsulata, are (according 
to Prof. Uhler) punctata, Fieb. They vary in colour and pattern 
like the other forms. The alar nervures are golden-yellow ; the 
abdominis dorsum varies from clear luteous to black; the venter 
varies from sordid-whitish to black (vid whitish-blotched with 
black). 
Long. (of vars. 1-4) 10°5-12 mm., lat. 3-4 mm. 
Var. 5, virescens, Blanch., is indistinguishable save by the more 
minute size, from V. undulata, but it seems to be confined to 
Chili. 
Long. 9-9.38 mm., lat. 3-3°2 mm. 
Unfortunately the figure in the Atlas of Gay’s work 
is not quite correct, either in structural details or in 
colouring. ‘The antenne in the figure represent those of 
an Hnithares, while the body is unduly depressed, and 
the proportions inaccurate. There are two forms, in both 
of which the dorsum abdominis is black: (a) Concolorous 
luteous (Paris Mus.); (6) hemielytra black; clavus 
