322 SAMUEL II. SCUDDBB ON THE 



minor groups, and by their aid, and almost entirely by their aid, we may distinguish 

 between orthopteroid, neuropteroid, and hemipteroid Palaeodictyoptera. 



PALAEODICTYOPTERA. 



Body more or less elongate, composed of three well-defined regions, head, thorax, and 

 abdomen; mouth parts as in modern Hexapoda, variously developed; antennae filiform, 

 simple ; eyes compound. Thorax three-jointed, subequally developed, each joint bearing 

 a pair of moderately long legs ; the meso- and metathoracic wings closely similar, equally 

 membranous, supported by a framework in which six principal stems are developed, the 

 first of which always forms the costal margin ; the mediastinal is simple or only provide:! 

 with superior branches, the scapular and internomedian simple or compound, the exter. 

 nomedian and anal nearly always compound, their branches almost always inferior ; 

 -generally most branches dichotomize; the membrane is usually more or less reticulate 

 with generally irregular polygonal cells ; stout and well-defined cross veins are rare ; the 

 costal area is generally scant, the anal area generally ample, often very ample, yet not so 

 much from depth as from distal extension; when at rest the wings appear in all cases to 

 have covered the abdomen as in modern cockroaches, white ants and Sialina; but although 

 there is some indication from their greater breadth that the hind wings were then folded. 

 they were never plaited like a fan as in modern Orbhopfcera. The abdomen was usually 

 lom>- and slender, composed of nine or ten joints, the last one sometimes furnished with a 

 pair of articulated appendages. 



[Orthopteroid Palaeodictyoptera.] 



Palaeoblattakiae So udder. 



The points in which the ancient cockroaches differed from existing types has been fully 

 pointed out in a comparatively recent paper, 1 and need not be repe ited here. The classi- 

 fication there proposed has been generally accepted and no little addition to our know- 

 ledge of ancient types of cockroaches has since been added. A number of undescribed 

 forms are in my hands from American deposits, including several new genera, and will be 

 made the subject of special papers. Recent explorations in Triassic beds of Colorado have 

 thrown new light" on the passage of the Palaeoblattariae to later types and it is announced 

 by Brongniart that he has discovered a cockroach in the middle Silurian. The figures he 

 has given, however (La Nature xiii. 116), though unsatisfactory, would lead us to suppose 

 the insect to belong to the neuropteroid Palaeodictyoptera. 



Protophasmioa Brongniart. 



■a 



A classification of the members of this group having been recently proposed by me 3 , 

 and as 1 intend to refer to them more fully on another occasion in fully describing and 



1 Mem. Bost. Soc. Nat. Hist., in, "23-134. here. Diet, elongata Gold, was place 1 in both Breyeria and 



2 Ainer. Journ. Sc., (3) xxvin, 199-203. Goldenbergia ! It was at first supposed to belong to Breveria 

 8 Proc. Amer. Acad. Acad. Arts. Sc., xx, 167-173. A and was aecidently left there after it was discovered that its 



careless error which crept into this paper may be corrected true place was in Goldenbergia. 



