March, 191 6.] CrAMPTON : ORIGIN OF WiNGS. 25 



principal fulcra, or pivots, used in the movements of flight. Two of 

 these fulcra are dorsal, and one is ventral (with regard to the at- 

 tachment of the wing). The anteriormost dorsal wing fulcrum (or 

 suralar fulcrum) is formed by the small sclerite sur of Figs, i, 6, 

 and 7, of Plate I (compare also Figs. 4 and 6 of Diptera and 

 Hymenoptera by Crampton, 1914 c, i. e., the sclerite designated as 

 "sur"; and sclerite similarly labeled in Fig. i by Crampton, 1914 

 a), which is always situated immediately behind the tegula {tg 

 of the above-mentioned figures). The posterior dorsal wing fulcrum 

 (or adanal fulcrum) is formed by a projecting region apt of Figs. 

 I, 6, and 7 (Plate I) which extends toward the anal veins (hence 

 the name adanal), which usually articulate with it. In some forms 

 this region may become detached to form a distinct sclerite, or plate. 

 Between these dorsal wing fulcra, is a small plate npt which is 

 present in practically all winged forms. From its location, and close 

 connection with the notum, I think that this articulatory ossicle is a 

 detached portion of the notum or tergum, and have therefore desig- 

 nated it as the notopterale (the term pteralia having been applied to 

 the alar ossicles in general by Groeschel, 191 1). The other dorsal 

 ossicles, are, for the most part, detached portions of the basal region 

 of the wing veins. The tegula {tg), however, is possibly merely a 

 thickening of the membrane. The sclerite m (Figs. 6 and 7) is the 

 only other dorsal ossicle of interest, and is mentioned because it dips 

 downward and unites with a plate on the lower surface of the wing, 

 as will presently be described. The various modifications of the 

 dorsal ossicles may be readily seen by comparing Figs, i, 6, and 7, of 

 Plate I, with Figs. 4 and 6 of Plate VII by Crampton. 1914 c, 

 homologous ossicles being designated by the same lettering in both 

 instances. 



The ventral fulcrum of the wing is formed by a dorsal projection 

 of the episternum and epimeron extending upward (along the suture 

 dividing the two pleural sclerites) as a narrow projecting region 

 figured in Fig. 5 of Plate I. This narrow neck-like region may 

 become detached to form a distinct plate in certain insects, but is 

 usually more or less rigid to form the pleural fulcrum of the wing 

 I'pieuro-alar fulcrum). 



Immediately in front of this fulcrum, at the base of the wing are 

 two basalar plates (Fig. 5, aha and pba) , which are sometimes in- 



