342 SAMUEL H. SCUDDER OX THE 



Hemeristia occidentals. 



Hemerist'ia occidentalis Dana, Amer. Journ. Sc, (2) xxxvn, 35, fig. 2; — Scudd., Amer. 

 Jouin. Sc, (2) xl, 269-271; — Ib., Mem. Bost. Soc. Nat. Hist., i, 191-192, pi. 6, figs. 1, 3; 

 — Ib., Geol. Mag., v, 217-218. 



Same deposits. 



Apparently allied to this, but too imperfect to warrant confidence in a definite state- 

 ment, is an insect (pi. 31, fig. 8) from the same deposits, received from Mr. R. D. Lacoe 

 under the number 2050. It certainly differs from the preceding in the development and 

 structure and curving disposition of what appear to be the internomedian vein; but the 

 outer half of the wing being lost, no scapular branch can be seen, although one would 

 look for it in the portion preserved. The course of what appear to be the externomedian 

 offshoots — at least as seen on the left side — lead one to suppose that such a branch 

 (or branches) must exist, and the general appearance of the insect is that of this family. 

 The head is transverse, well rounded and strongly convex, and obscure parts in front of it 

 take on a triangular form. 



Gerarina fam. nov. 



Wings variable in form but usually not so elongate as in the other types, and sometimes 

 remarkably short in proportion to their width. The mediastinal vein is simple, runs close 

 to and terminates in the margin, usually far toward the tip of the wing, and sends 

 numerous oblique offshoots to the margin. The scapular is generally the most important 

 vein in the wing, running parallel to the mediastinal, and emitting several or many longi- 

 tudinally oblique branches, most of them generally in the outer half of its course; these 

 branches may be perfectly simple, the outermost forked a little, or all more or less forked, 

 and then liable to appear arborescent; even when most numerous they rarely occupy more 

 or much more than the tip of the wing, on account of their longitudinality and their lack 

 of tendency to spread. The externomedian vein is generally less, often far less, impor- 

 tant than the scapular, and has two or "more branches, the offshoots running parallel to 

 those of the preceding vein, which they resemble so as to be indistinguishable from them 

 Avhen their origin is concealed; the innermost branch never strikes the margin in the 

 basal half of the wing. In one curious type (Megathentomum) this seems to be the most 

 important vein in the wing, and all its branches fall on the broad apical margin. The in. 

 ternomedian vein is generally reduced to a simple vein, or to a lesser imitation of the 

 externomedian vein. The anal area generally extends to or beyond the middle of the 

 lower margin of the wing, and seems usually to be filled with more or less oblique and 

 more or less frequent nervules running to the margin. 



This family differs from all the preceeding in that the scapular vein has a considerable 

 number of offshoots depending from the main vein itself and not from a simple principal 

 branch. Nor is there any modern type to which it can be compared. A considerable pro- 

 portion of the forms are now for the first time described, and all are American, excepting 

 one which is very closely allied to an American form, falling into the same genus, which 

 is in many respects widely different from the other types. 



