PROC. ENT. SOC. WASH., VOL. 20, NO. 2, FEB., 1918 31 



Tischeria and the Leucopterigidae on the other hand resemble 

 Opostega in a number of striking peculiarities. The lateral ridge 

 (LtR) which is such a prominent character in Opostega is also 

 present and quite discernible in two elements in Nepticula and 

 Ectodemia, as a short endoskeletal arm (Lrd) (fig. 16) branching 

 out on the dorsum of the epicranium from the angle of the an- 

 tennal ring, and a more or less extended ventro-lateral ridge 

 (Lrv, figs. 13, 17). A little constriction of the head in the ocellar 

 region and the two branches unite to form the lateral ridge of 

 Opostega. The posterior dorsal regions of the epicranium de- 

 veloped into thin, flattened, triangular, blade-like projections in 

 the Leucopterigidae, Tischeriidae, and Nepticulidae are still 

 further narrowed in Opostega until they are represented only 

 by the narrow, ribbon-like projections (/?/). Most significant 

 of all, however, is the development of the hypostoma in all these 

 forms. The tendency is always toward an enlargement and 

 anterior movement of the triangular plates and a consequent 

 crowding forward and reduction in size of the labial and maxil- 

 lary parts. In the Leucopterigidae (fig. 32) this tendency has dis- 

 torted a normally proportion stipes which has not accommodated 

 itself to the change and forced it to slop over the anterior margin 

 of the epicranium and a large part of the area occupied by the 

 postmentum. 5 In Tischeria the labial palps have accommodated 

 themselves better and the maxillary stipes are narrowed, though 

 still rather long. The Nepticulidae show a much greater reduc- 

 tion of the labium and maxillae and in Opostega we have the most 

 extreme development with the triangular plates of hypostoma 

 well forward and the labium and maxillae crowded under and 

 almost completely covered by the mandibles. Another interest- 

 ing character is the tendency for the ridges of hypostoma to 

 diverge posteriorly rather than run parallel as they do in the 

 normal feeding Lepidoptera. We see the beginnings of this in 

 Mnemonica (Comp. Busctf and Boving [3] Plate X, fig. 7) where 



mid-ventral surface of the head. I would like to take this opportunity 

 to correct a former statement of mine (5, pp. 155, 156) that the head of 

 I'hiillai-nixlix showed tendencies which pointed to an origin different 

 from that of the Gradlariidae. Leucanthiza, which is unquestionably a 

 (iracilariid and very near t<> Phyllocnistis indicates that Phyllocnislis 

 is a true C.racilariid. This skives us another defining character for t lie 

 family for nowhere else, as far as I know, has the sap-feeding lialiii 

 developed. 



Tragardh i(), p. .'!.">) with his usual kceness in such matter,- notes the 

 exceptional character of the stipes of Li'iico/ilcni (Cemiostoma) and con- 

 siders ihat it is their greater development which is responsible lor their 

 peculiar form. He notes that an even higher degree of development 

 along (lie same lines lias taken place in Lithocolletis. \ ihink the lines 

 of progress are.]".-' opposite in the<e two forms. In LeUCOptera the stipe- 

 is not growing larger. It is being crowded by (he hypostoma. 



