574 



INSECTA. 



[XYL. 



villosus, Scudder, 1884, Mem. Bost. Soc. 



Nat. Hist., vol. 3, p. 291, Coal Meas. 

 XYLOBIUS, Dawson, 1860, Quar. Jour. Geo. 

 Soc., vol. 16, p. 268. [Ety. xylobius, liv- 

 ing in wood.] Body crustaceous, cylin- 

 drical, elongate, rolling spirally ; seg- 

 ments thirty or more, anterior ones 

 smooth, posterior ones furrowed; legs 

 small, numerous ; labrum quadrilateral, 

 divided by notches or joints into three 

 portions; mandibles two-jointed, last 

 ovate and pointed ; eyes ten or more on 

 each side. Type X. sigillarise. 



dawsoni, Scudder, 1868, Mem. Bost. Soc. 

 Nat. Hist., vol. 2, p. 236, and Acad. 

 Geol., p. 496, Coal Meas. 



fractus, Scudder, 1868, Mem. Bost. Soc. 



Nat. Hist., vol. 2, p. 234, and Acad. 



Geol., p. 496, Coal Meas. 

 mazonius, Zittel, 



1885, Handbuch 



der Pal., p. 730, 



Coal Meas. TO9~ / j 



sigillarue, Dawson, Kf a/Mi 



1860, Quar. Jour. ^ iSr 



Geo. Soc., vol. 16, 



p 271 Coal Meas FIG. 1073. Xylobius 

 BimiliR, Scudder, ^fthDafous ^n'lhf 



1868, Mem. Bost. S Whe mouth, en"- 



Soc. Nat. Hist., larged. 



vol. 2, p. 234, and Acad. Geol., p. 496, 



Coal Meas. 



CLASS INSECTA. 



INSECTS are possessed of head, thorax, and abdomen. Three pairs of legs and 

 one pair of antennae belong to them in their perfect state. They are the highest 



ERRATA. 



Fig. 1072 is Euphoberia granosa. 

 Figs. 1074 and 1075 are transposed. 



nued as follows : sody generally elongated ; mouth parts variously developed ; 

 antennae filiform ; thoracic joints subequally developed ; legs moderately large ; meso 

 and metathoracic wings closely similar, equally membranous ; the six principal 

 veins always developed ; the marginal simple, and forming the costal border ; the 

 mediastinal generally simple or with superior branches only ; the other veins usu- 

 ally dichotomize; stout and well defined cross veins rare; membrane generally 

 reticulate ; wings in repose lying on the abdomen ; the anal area of hind wings, 

 though usually of great distal extension, never plaited, though sometimes broadly 

 folded; abdomen "usually long and slender, the last joint often furnished with sim- 

 ple articulated appendages. 



ORDER PAL^EODICTYOPTERA. 



FAMILY GERARIID^E. Adiphlebia, Gerarus, Megathentomum, Polyernus. 



FAMILY HEMERISTID^E. Chrestotes, Hemeristia, Lithentomum. 



FAMILY HOMOTHETID^E. Anthracothremma, Cheliphlebia, Didymophleps, 



Encsenus, Genentomum, Genopteryx, Gerapompus, Homothetus. 

 FAMILY MYLACRID^E. Lithomylacris, Mylacris, Necymylacris, Paromylacris, 



Promylacris. 

 FAMILY PAL^OBLATTINID^-:. Archymylacris, Etoblattina, Gerablattina, 



Oryctoblattina, Petrablattina. 



FAMILY PAL^EOPTERINIDJE. Aethophlebia, Dieconeura, Miamia, Propteticus. 

 FAMILY PAL^EEPHEMERID^E. Ephemerites, Geraphemera, Platephemera. 



