July D. tigrina emerges and all three species fly together during August and into September when they fly with Tipula ultima Alex., T. unifasciata Lw., etc. It is curious that no other species of Limnobiinæ occur in the thamnophytic association frequented by Dicranoptycha. All three species of this genus as discussed above have habits that are generally similar to one another. They are usually found resting quietly on the upper surface of the leaves but fly readily and on slight disturbance. Pairs in copulation are often found resting, the bodies directed away from one another and the wings folded over the abdomen. While thus united they fly readily, sometimes the female taking the initiative, sometimes the rather smaller male. The eggs are deposited in the soft earth in these situations.

NATURAL AFFINITIES

In the Monographs (1869) Osten Sacken included the genus Dicranoptycha in his tribe (section) Limnobina anomala, or, as it subsequently became known, the Rhamphidini, and still later the Antochini. A recent survey of the immature stages of several Antochine genera has shown that the tribe is merely an artificial grouping based on superficial resemblance of the adult flies. This heterogeneous assemblage includes representatives of at least three other tribes, Dicranoptycha, together with Antocha, Elliptera, Rhamphidia, etc., showing an undeniable affinity with the Limnobiini, whereas Teucholabis, Elephantomyia, etc., show an equally clear relationship with the Eriopterini. Moreover a close phylogenetic relationship with the lowermost subtribes of the Hexatomini (Ularia, Epiphragmaria, etc.), is easily apparent.

Dicranoptycha shows the closest affinities with Antocha and Rhamphidia. The larvæ of these three genera, each of which typifies a division, show the following common characters:

Abdominal segments with basal transverse creeping welts or areas of microscopic points. The massive compact head-capsule with the præfrontal sclerite large, distinct, the externo-lateral plates large, mussel-shaped and very thin. The mentum is not completely divided medially. The maxillæ are large and of primitive structure, the cardines and stipites distinct, the two distal lobes large, subequal in size, covered with hairs and bearing sensory organs. Mandibles with one or more dorsal and two or more ventral teeth in addition to the apical point.

The differences between these allied divisions are best indicated by a key.

LARVAE

PUPAE

THE SUBTRIBE DICRANOPTYCHA

A Key to the Species of Dicranoptycha

LARVAE

DESCRIPTION OF THE SPECIES

1916 Dicranoptycha winnemana Alexander; Proc. Acad. Nat. Sci. Phila., pp. 500, 501; Pl. 25, fig. 12.

Coloration varying from white to almost black depending on the nature and amount of the food eaten which shows clearly through the transparent integument. The fat-bodies likewise show through and give a white color to the larva especially after death.

Form very elongate (fig. 1), body terete; integument very glabrous, transparent and glassy. Prothoracic segment a little longer than the mesothorax which, in turn, slightly exceeds the metathorax. The intermediate abdominal segments are elongated. The basal ring of sternites two to eight bears a transverse band or area of microscopic chitinized spicules, the one on the eighth segment split lengthwise by a capillary line. A similar band occurs in the same position on the dorsum of the eighth segment but the pleural region is devoid of such a band.

Spiracular disk (fig. 8) moderate in size, obliquely truncated, surrounded by four lobes, a pair of small, slender, lateral lobes and short, broader ventral lobes. The usual dorso-median lobe is lacking but its position is indicated by a gently rounded convexity. The inner face of the lateral lobe bears a narrow semi-lunate black mark with the concavity toward the spiracle, the proximal end acutely pointed. The ventral lobes bear a similar but smaller subrectangular black mark. A pale and usually indistinct dusky mark occupies the inner face of the dorsal lobe. On the disk between, and slightly below the level of, the spiracles is a large brown triangular or V-shaped mark. The spiracles are small, separated from one another by a distance equal to about 2.5 to 3 times the diameter of one; the center-piece of the spiracle is black, the ring yellow surrounded by an outer dusky margin. Anal gills fleshy and protuberant as a blunt ring surrounding the anus (fig. 10).

Head-capsule (fig. 2) of the compact, massive type of the Limnobiini; præfrontal sclerite (fig. 3) large and distinct; the sclerite broad with the sides