578 



INSECTA. 



[HAP. LIT. 



barnesi, Scudder. 1867, Can. Nat. and 

 Geol. 2d set-., vol. 3, p. 202, and Acad. 

 Geol., p. 386, Coal Meas. 



FIG. 1085. Haplophlebium barn 



A fern covers part of the wing 



longipennis, Scudder, 1884, Proc. Amer. 



Acad., vol. 20, p. 172, Coal Meas. 

 HAPLOTICHNUS, n. gen. [Ety. haplotes, plain- 

 ness, simplicity ; ichnos, track.] Sim- 

 ple, small, half-cylindrical trails running 

 in any direction. Supposed to have 

 been made by the larva or pupa of 

 some palseodictyopterous insect. Type 

 H. indianensis. 



indianensis, n. sp. A simple half-cylin- 

 drical trail, needle-like in size, running 

 in straight or crooked lines, or cross- 

 ing itself. Found in the upper part of 

 the Kaskaskia Group, at the Whetstone 

 quarries in Orange County, Indiana. 



FIG. 1086. Haplotichnus indlaneusls. 



The remains of insects found in the 

 Palaeozoic rocks occur under, such cir- 

 cumstances as to induce the belief they 

 were more or less aquatic in their habits, 

 and frequented swamps and shores of 

 bays and inlets. The Whetstone quar- 

 ries of Orange County, Indiana, are 

 yellowish white, slaty mud-rocks re- 

 sembling, in appearance, the Solen- 

 hofen slates, but coarser in texture. 

 They are limited in extent, and may be 

 fairly presumed to represent the muddy 

 shore of some bay or internal sea of 

 Subcarboniferous age. The slaty layers 

 are covered more or less upon the 

 upper surface with trail-furrows, and 

 on the under surface with elevated 

 lines, showing the trails were made in 

 mud, which afterward hardened, and 

 was then covered with a thin deposit 

 of mud which was tracked and hard- 

 ened and covered, and so on in one 

 series after another throughout the 

 whole thickness of the slaty deposit. 

 Many of the living Dictyoptera are 



aquatic in their habits in the larva and 

 pupa state, and it is not until the per- 

 fect insect is about to emerge from the 

 skin of the pupa that it 

 creeps out of the water 

 on the muddy shore or 

 stonee, or climbs the stems 

 and leaves of aquatic 

 plants, and from this 

 position the imago springs 

 into an aerial habitat. 

 The trails on the Whet- 

 stone slates were evidently 

 made by animals, and 

 all the evidence seems to indicate they 

 were made by insects, though the 

 evidence may not be either clear or 

 conclusive in the latter respect. Under 

 these circumstances the author has 

 selected three common but distinct 

 trails, and given then generic names ; 

 viz., Haplotichnus, Plangtichnus, and 

 Treptichnus. 



HEMERISTIA, Dana, 1864, Am. Jour. Sci. and 

 Arts, 2d ser., vol. 37, p. 34. [Ety. htm- 

 era, day ; istia, house.] Scapular branch 

 strongly arcuate, at its base distant 

 from the main stem, and at first taking 

 the course of its basal offshoot. Type 

 H. occidentalis. 



occidentalis, Dana, 1864, Am. Jour. Sci. 

 and Arts, 2d ser., vol. 37, p. 34, Coal 

 Meas. 



H O M O T HETUS, 



Scudder, 

 1867, Can. 

 Nat. and 

 Geol., 2d 

 ser., vol. 

 3, p. 202. 

 [Ety. ho- 

 mos, simi- 

 lar ; thetos, 



placed.] Mediastinal vein extremely 

 long, scarcely surpassed by the scapu- 

 lar, and with scarcely any branches to 

 the costa; externo-median vein with 

 only a few branches in the outer fourth 

 of the wing; interno-median vein sim- 

 ilar to the last. Type H. fossilis. 

 fossilis, Scudder, 1867, Can. Nat. and 

 Geol., 2d ser., vol. 3, p. 202, and Acad. 

 Geol., p. 525, Upper Devonian. 



Libellula, Linnaeus. Not a Palaeozoic genus. 

 carbonaria, see Cheliphlebia carbonaria. 



LITHENTOMUM, Scudder, 1867, Can. Nat. and 

 Geol., 2d ser., vol. 3, p. 202. [Ety. 

 lithos, stone ; entomon, an insect.] Main 



FIG. 1087. Homothetus 

 fossilis. 



FIG. 1088. Lithentomum hartti. 



scapular branch with a single, or at 

 most two branches, which are almost 

 wholly longitudinal. Type L. hartti. 



