Abdomen narrow subcylindrical, tapering posteriorly. Segments 1–6 dark brown, heavily marked with dull-blackish in the form of a transverse basal band, from which project two elongated longitudinal marks, one on either side of the median line, and reaching to within a short distance of the apex of each segment; 7–8 paler brown, with similar blackish basal band, but with shorter longitudinal projecting marks, reaching only about half-way along each segment; 9 pale brown, with very narrow blackish basal band and slender longitudinal projecting marks; 10 pale brown, with narrow blackish basal band and no projecting marks. Ventral valve cleft in middle, its margin forming two rounded lobes (fig. 2, f); those of the other New Zealand species are shown for comparison in fig. 2, d, e. Cerci (partially shrivelled) somewhat longer than abdomen, brown, with darker segmental rings. Appendix dorsalis much reduced, only 3 mm. long, much shrivelled, with numerous minute obsolescent segments.

Fig. 1.—Ameletus fiavitinctus n. sp.: female imago, wings. × 5·4. The shaded portions of the wing represent the parts coloured pale transparent yellow, the unshaded portions those which are hyaline. Cu, cubitus; M, media; R, radius; So, subcosta. Note the positions of the two groups of thickened cross-veins and of the bullae in the forewing.

Wings brilliant, most of the membrane a pale transparent yellowish, but with certain areas left absolutely hyaline, as shown in fig. 1. It will be seen that these areas are chiefly those formed where the very irregularly placed cross-veins lie farthest apart. Veins blackish. Forewing with two groups of thickened black cross-veins between Sc, R₁, and R₂, one set being about half-way along the wing, the other below the proximal part of the pterostigma. There is a series of five definite spots or bullae on the forewing, on Sc, R₁, R₂, R₃, and R₄ respectively, the first three being large and situated in the midst of the first set of thickened cross-veins already mentioned, while the last two are smaller and situated below them. In shape the forewing is similar to that of Ameletus ornatus Eaton. Hind-wing with the humeral angle as shown in fig. 2, c; the same portion of the hindwings of A. perscitus Eaton and A. ornatus Eaton are shown for comparison in fig. 2, a, b.

♀. Subimago: The specimen described above was captured in the subimaginal stage, but had changed into the imaginal stage before it was killed. The subimaginal stage has opaque wings, remarkably variegated in the bold manner shown in the subimago of Atalophlebia versicolor Eaton.

Male unknown.

Type.—Holotype female imago in Cawthron Institute collection.

Abdomen deep chocolate-brown, faintly mottled with somewhat paler brown; in shape slender subcylindrical, slightly narrowed at 5–7, broadening again at 8–9; 9 much wider than 10, broader apically than basally. Cerci 23 mm. long, dark chocolate-brown, strongly formed, slightly hairy, the segments cylindrical with narrow black basal rings. Appendix dorsalis vestigial, 1 mm. long, with few segments.

Appendages of the same type as in I. hudsoni McL., but with the following differences: Forceps basis slightly shorter and cut-off obliquely on either side of its posterior margin, which, between the bases of the forceps, is cut straight off, not double-curved as in I. hudsoni McL.; pale brown in colour, with a large shield-shaped central area of dark brown, with two black dots on it. Forceps with segment 1 broad, as in I. hudsoni McL., but more sharply angulated apically on the inner side; segment 2 very

Fig. 3.—Ventral view of male appendages in the genus Ichthybotus Eaton: a, in I. bicolor n. sp.; b, in I. hudsoni McL. × 14. 1, 2, 3, 4, the four segments of the forceps; 9, 10, the last two abdominal segments; ad, appendix dorsalis; c, cercus (the right cercus is omitted); fb, forceps basis; p, penis.
Fig. 4.—Left lateral view of male appendages in the genus Ichthybotus Eaton: a, in I. bicolor n. sp.; b, in I. hudsoni McL. × 14. Right cercus and right forceps omitted. (For lettering see fig. 3.)
Fig. 5.—Outline of ventral valve in the female of a, Ichthybotus bicolor n. sp., and b, I. hudsoni McL. × 14.

long (but not so long as in I. hudsoni McL.), narrower, and with a row of minute hairs along the basal two-thirds of the inner margin; segments 3–4 very short, subequal. Penis more prominently lobed than in I. hudsoni McL., each lobe carrying a set of minute stiff hairs. Cerci 23 mm. long, dark chocolate-brown, strongly formed, slightly hairy, the segments cylindrical with narrow black basal rings; those of I. hudsoni McL. are quite hairless, yellowish-brown or orange-brown, with broad dark basal rings. Appendix dorsalis vestigial, 1 mm. long, with few segments.

In order that a careful comparison may be made between the appendages of the males of the two species, I have figured them both ventrally in fig. 3, and laterally in fig. 4.

The male may at once be distinguished from that of I. hudsoni McL. by its very dark coloration and its brown hindwings, as well as by the morphological differences given for the appendages.