210 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi. 



thick as those which precede it. The abdomen is egg-shaped, with its 

 tip drawn out into a tube thrice as long as it is thick, with four long 

 bristles at its end, and the abdomen is furnished with bristles at each 

 of its sutures. The wings do not reach the tip of the abdomen. 

 They are white and slightly transparent and fringed with ])lack hairs. 

 In its larva state it has a more slender linear form with a dull greenish 

 yellow head, a white thorax with a broad black band anteriorly, a pale 

 red abdomen with a black band at its tip, and whitish legs." 



F08S1L THYHANOPTEKA. 



Tiny though they are, these insects are not unknown as fossils. The 

 White River deposits are the only ones in this country from which they 

 are yet known. Three species, representing as many genera, have been 

 found there in Tertiary rocks, and have been described by Dr. S. H. 

 Scudder (174, .336), whose descriptions of these insects follow. The 

 last two genera are extinct. Of the genus ^LlauotJiripsi^ no living 

 representative has as yet been found in this country, though a species 

 of this genus is known in Europe. 



MELANOTHRIPS EXTINCTA Scudder. 



Melanothrips e.rlincta Scudder, Bull. U. S. Geol. (leog. Surv. Terr., I, 1875, p. 221; 

 Kept. U. S. Geol. Snrv. Terr., XIII, 1890, p. 371. 



"Head small, tapering; the only appendages visible are the antennte; 

 these are only sufficiently ])reserved to recognize that they are very 

 long and slender, longer than the thorax. The thorax is rather small, 

 quadrate; wings nearly as long as the body, fringed on the costal 

 border as in PalsQothrl'ps fomUlH. The abdomen is composed of only 

 eight joints, but is very long and very tapering, fusiform, the last joint 

 produced, as usual in the Physapods; the third joint is the l)roadest;i 

 of the wings only the costal ])order ;iind a part of one of the longi- 

 tudinal veins can be seen; there arc no remains of legs. 



"Length of l)ody, 2.2 mm. ; of antenna?, O.S mm. ; of head, 0.14 mm.; 

 of thorax, 0.5 mm.; of abdomen, 1.56 mm.; greatest breadth of 

 abdomen, 0.5 nun. 



"Chagrin Valley, White River, Colorado. One specimen, WJ; 

 Denton."" 



Genus LITH ADOTHRIPS Scvidder. 



Lit/i(t(lo(hrij)s ScuDDEK, Bull. U. 8. Geol. (^eog. Surv. Terr., I, 1875, p. 221; Kept. 

 U. S. Geol. Surv. Terr., XIII, 1890, p. 372. 



"Allied to Melanothrips Haliday. The head is large, broad, globose;; 

 the eyes exceedingly large, globose, each occupying on a superior 

 view fully one-third of the head; the antenna very slender, equal, as 

 long as the thorax, the joints eight or nine in number, cylindrical, 

 equal, scarcely enlarging toward their tips. The prothorax is no 



