E. H. Sellards — Types of Permian Insects. 



345 



Art. XXXIII. 



Types of Permian Insects; by E. H. 

 Sellards. 



[Continued from vol. xxii, p. 258, Sept. 1906.] 



Part II. — Plectoptera. 



Ephemerids have been until very recently unknown from 

 Permian deposits. The group is scantily represented in the 

 Russian Permian, according to Handlirsch, by one imperfectly 

 preserved wing and three larval forms.* That Ephemerids 

 were present in considerable numbers during Permian time 

 is, however, clearly indicated by the collections made from 

 the Kansas Permian. True Ephemerids make up a conspicu- 

 ous element in the insect fauna of these deposits. 



Trotereismephemeridce, new family. 



The insects of this new family are true Ephemerids. In 

 the general shape of the wings and the body, as well as 

 in the manner of holding the 

 body, they very much resemble 1 



many of the modern large 

 Ephemerids. The prothorax 

 and head are of medium size ; 

 the thorax is large and arched; 

 the mesothorax and metathorax 

 are ■ equal in size or nearly so ; 

 the abdomen is long and slen- 

 der and terminates in stream- 

 The wings are elongate 



border 



ers. 



with rounded inner 

 the two pairs are 

 developed, or nearly so. The 

 venation of the wing is of a 



Fig. 1. Arrangement of veins at the 



ecuallv base of the wing as seen in the type 



genas of the family Protereismephe- 

 meridas. Veins drawn to scale from 

 nature. C, costa ; Sc, snbcosta ; E, 

 radius ; Es, radial sector ; M, media ; 

 Cui, first division of the cubitus ; Cu 2 

 second division of cubitus ; A, first 

 anal ; Cb, costal brace. Enlarged 6 



fixed and characteristic type, 



indicating a well established 



family. The snbcosta, as is 



usual with Ephemerids, lies times 



close to the border and extends 



to the apex of the wing. The radius is strong at the base and 



extends j)arallel to the snbcosta to the apex. The radial sector 



is very uniform throughout the family. Its divisions, as is true 



also of other veins of the wing, are by sets of threes, the typical 



number being three sets of three veins each, or nine branches to 



the sector in all. The first division of the sector is commonly 



*tiber einige Insektenreste aus der Perm formation Eusslands. Memoires 

 de L'Academie Imperiale des Sciences de St.-Petersbourg, (ser. 8) vol. xvi, 

 No. 5, 1904, pp. 6-7 ; Die Fossilen Insekten, Lieferung III, pp. 386-387, 1906. 



