Vol. 1.] 



Woodivortli. — Wing Veins of Insects. 



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dragonflies; Amans ('85), who gives us the only comparative 

 study of the subject and covers all the principal groups; and 

 Lowne ('90-95), who, confining himself to a single insect, the 

 blowfly, makes a notable contribution by his very complete 

 and painstaking account of the structure. 



The investigation of Amans is the most nearly in line with 

 the question of articulation now under consideration. As a 

 result of his investigation he reached the conclusion that all 

 the parts of the entire articular mechanism are comparable, 



FIG. 11. Wing articulation in ^Sschna A, from above; B, from within; C, in section. 



s, sc, scutum; scl, scutellum; pscl, postscutellum; psc. praescutum ; ips, inter- 

 pleural suture; md, muscle disks; ms7i, mesonotum ; mtn, raetanotum; w. wing; 

 wr, wing-roots; aa, articular apophyses; sm, depressor muscle : em, elevator muscle; 

 hp, hinge piece; p, pleur;e. 1-7 veins. 



piece by piece, throughout the whole series of insects; he 

 includes in this category of homologous structures not only 

 the hinge proper, but also all the veins that reach the base of 

 the wing. 



Upon this point there is room for a decided difference of 

 opinion, there being abundant reason for the view, first sug- 

 gested by Chabrier ('20-22) and adopted by Pettigrew ('71) 

 and Jousset de Bellesme ('79), that the Odonata present a 

 different type of structure from that found in the higher 

 insects. 



A reexamination of the structure of .Eschna, the insect 

 studied by both von Lendenfeldt and Amans, is highly desir- 

 able. Both of these authors recognize five veins as reaching 



