S. H. SCUDDER ON PALAEOZOIC COCKROACHES. 83 



belonging to the anal field, which he describes as having " many delicate, radiating, longi- 

 tudinal veins, connected by scarcely perceptible delicate cross veins." Length, 11 mm. ; 

 breadth, 4 mm. 



This insect is, perhaps, the most complete of any of the palaeozoic species of cockroach, 

 the abdomen being almost comjjletely preserved, but the legs unfortunately wanting. The 

 pronotal shield is shaped somewhat as in Etdbl. earbonaria, being longitudinally oval, 

 broadest near the posterior margin, tapering toward the rounded front, the hind margin 

 apparently broadly rounded ; it is somewhat gibbous, and shows in the middle and laterally 

 weak longitudinal furrows ; it is 7 mm. long, and 6.25 mm. broad. The mesothorax is 

 very short and inconspicuous ; the meta thorax quadilateral, nearly as long as broad, broadest 

 in front, and narrowing rapidly behind ; the front and hind borders are slightly ai'cuate, the 

 curve opening posteriorly, the lateral angles rounded, the surface marked by weak median, 

 longitudinal and transverse furrows; length, 2.75 mm., breadth behind, 2 mm. The abdo- 

 men is extraordinarily slender, as it is in no modern types, giving the insect a remarkably 

 strange aspect; seven segments are preserved, and these grow gradually larger and broader 

 posteriorly; they are sharply separated from each other, and the lateral margins somewhat 

 upturned; the whole abdomen is 8.5 mm. long; its breadth at base is 1.6 mm.; at the 

 end of the seventh segment 2.2 mm. 



Goldenberg remarks of this insect, that it is by far the most complete and best preserved 

 of all that have yet been found in the carboniferous formation (Anthracobl. sopita was 

 not then known); and that it presents so many anomalies in not unimportant parts of 

 its structure, separating it from all hitherto known cockroaches, whether living or fossil, as 

 to render it highly probable that it should be considered a peculiar extinct genus, either 

 belonging to the family of cockroaches, or falling very near it. 



So little, however, is yet known of parts other than the wings in this genus, and as 

 the wings appear by their neuration to fall within this genus, it has seemed the best way 

 to place it here, at least until new examination shall give us a better clue to its true affini- 

 ties. Should the neuration prove clearly distinct from the other members of this genus, 

 there can be no doubt that it should stand by itself. 



The single specimen found was discovered in a bluish shale, in the Skalley-shaft of the 

 Hirschbach coal-pit at Saarbriicken, Germany. Middle carboniferous. 



Archimylacris (fipzvi /j.uXaxpi<;) 

 Archimylacris Scudd., Daws. Acad. Geol., 2d ed., 388 (186S). 



The mediastinal vein of the front wing runs parallel to and not distant from the costal 

 margin to a little beyond the middle of the wing, occupying less than one-fourth the 

 breadth of the wing, and emitting a considerable number of mostly forked, very oblique, 

 but still short branches. The scapular vein is considerably and pretty regularly curved, in 

 the same sense as the costal margin, but rather more strongly than it, lies rather distant 

 from the mediastinal vein, and, beginning to branch at some distance before the middle of 

 the wing, occupies with its branches, in the apical half of the wing, an average of nearly or 

 quite one-half the breadth of the wing; its trend, however, is so far downward that, trav- 

 ersing the apex of the wing obliquely, it terminates below the tip; it emits a large number 

 of branches, the general direction of which is similar to those of the mediastinal vein; 

 they fork repeatedly, so that the area is closely crowded with veins. The externomedian 



