554 PROCEEDTXG$^ OF THE XATTOXAL MUS!EtI]\f. vor.. xxxvi. 



G. Protlioracic spiracle j^lates closely associated with me&othorax 

 ill the nymph (14, IG, Sp). In the adult they unite with each other 

 across the back, thus forming a complete spiracular dorsum (18, [/) 

 which fuses with mesothorax in front of declivous part of the latter 

 formed by dorsal parts of episterna, 



7. Trochantin lacking in both nymphs and adults. 



8. Coxa? of all the segments in the nymphs articulate ventrally 

 with the sternum by a special condyle (11, IG, d). 



0. Episterna of mesothorax and metathorax subdivided in both 

 adults (18, ID) and nymphs (14, IG) into an upper plate (eps) and 

 a lower plate [Ep^). In mesothorax the upi)er meets its fellow of 

 opposite side along the mid dorsal line between the true mesonotum 

 and the protlioracic spiracular bridge (18 g). An old nynipli (14) 

 shows an intermediate condition of this modification. In metathorax 

 the upper plate of episternum (cps..) fused with preceding epimerum 

 (Ejym^). Hence, the two oblique sutures on side of combined meso- 

 and metapleura are the two pleural sutures (IG, 18, PS), while the 

 incomplete middle one is the renmant of the intersegmental suture. 

 In metathorax (he cpimtu'a ( 18 Kp)ii) meet each other along the mid 

 ventral line behind metasterinun, just as do episterna of mesothorax 

 in front of mesotergum. 



10. Pleural wing ]n-ocess (18, ID) divided into two arms, the pos- 

 terior of which is the true wing process ( IIV) articulating with 

 wing, while the anterior (//) is an arm supporting the large costal 

 lobe of humeral angle of the wing. 



11. The flexible bases of Aving veins (17) merge into edges of 

 notum as in P^ihemerida. Only one distinct axillaiy is present 

 (17, lA.r). r>ase of the costa (17, 181, C) forms a large tripartite 

 lol)e at humeral angle of wing su])ported on anterior arm (//) of wing 

 process (18, ID). ^Median point of wing base, formed principally 

 by base of radius, articulates, by a venlral process, with true pleural 

 wing process (18, ID, ^YP). This process thus corresponds with 

 second axillary of other orders. 



Lendenfeld (1881) has made an exhaustive study of the details 

 of the tlioracic structure and Ihe wing articulation in Odonata. If 

 the reader is interested in minutiu' and in cumbrous Latin names he is 

 referred to the Avork of this author. Lendenfeld's nomenclature 

 can not lie adopted because it is not based on the idea of serial seg- 

 mental homology. 



The muscles of the wings in Odonata dilfer from those of all other 

 orders in being inserted upon the bases of the wings instead of upon 

 the neighboring parts of the notum and iileurum. As described by 

 Lendenfeld (1881) the set of eight muscles in each wing are as fol- 

 lows: (1) Ahdifcfor, (2) proiu/for i'{t(II/ primi, (3) fexor^ (4) fexor 

 radii guinti, (5) addiutor radi'/ <iii'niti, (G) pronator^ (7) .^yiphiaiop. 



