270 DR. PETT1GREW ON THE MECHANISM OF FLIGHT 



rig. gi. 



Left wing of the Albatros : def, anterior or thick margin of pinion; bac, posterior or thin 

 margin, composed of the primary (b), secondary (a), and tertiary (c) feathers. In this wing 

 the first primary is the longest, the primary coverts and subcoverts being unusually long and 

 strong. The secondary coverts and subcoverts occupy the body of the wing (ed), and are so 

 numerous that they effectually prevent any escape of wind between them during the return or 

 up stroke. This wing, which I have in my possession, measures over 6 feet in length. 

 Pig, 65. Bight wing of Beetle, dorsal surface. This wing somewhat resembles this Kestrel's (fig. 63) in 



shape. It lias an anterior thick margin, def. 



b a c. Strong 



nervurcs run along the anterior margin (d) until they reach the joint (e), where the wing folds 

 upon itself in repose. Here they split up and divaricate and gradually become smaller and 



mar 







.no 



Fi 



ncrvures radiate in graceful curves from the root of the wing. These also become finer as they 

 reach the posterior or thin margin (ca). r, root of the wing with its complex compound 

 joint : the wing of the beetle bears a certain analogy to that of the bat, the nervines running 

 along the anterior margin (d) of the wing resembling the humerus (fig. 00 d) and forearm of 

 the bat, the joint e of the beetle's wing (fig. 65 e) corresponding to the carpal or wrist-joint 

 (e, fig. 06) of the bat, the terminal or distal nervure of the beetle (fig. 65 fb) to the phalanges 

 of the bat (fig. 00/ b) . The parts marked/5 (figs. 05 & 00) may in both instances be likened to 

 the primary feathers of the bird, that marked a to the secondary ones. In the wings of the 

 beetle and bat no air can possibly escape through them during the return or up stroke. 

 Bight wing of the bat, dorsal surface : def, anterior or thick margin of the wing, supported by 

 the bones of the arm, forearm, and hand (first and second phalanges) ; a b, posterior or thin 

 margin, supported by the remaining phalanges, by the side of the body, and by the foot. 



g. 67. Right Ming of the Red-legged Partridge, dorsal aspect. 



exam 



wing ; 



Alb 



of the long ribbon-shaped wing: bac, primary (b), secondary (a), and tertiary {c), feathers 



with 



each other. This wing, like the Kestrel's (fig. 03), was drawn from a specimen held against the 



light, the object being to display the mutual relation of the feathers to each other, and how the 

 feathers overlap. 



* 68. Bight wing of the Beetle [Goliathus rnicans), as seen from behind and from beneath. When 



so newed, the anterior or thick margin (df) and the posterior or thin margin (be) cross each 

 other and form a true helix or screw. 



Kg. 69. Bight wing of the Bat as sec, from behind and from beneath. When so regarded, the anterior or 



Uuck nnngn, (df) of the wing displays different enrves from those met with on the posterior (4 c) 



or t,m margm, the anterior ami posterior margins crossing caeli other, as in the blades of a 



screw propeller. 



Fis. 70. 



beneath 



Flff, 71. 



(fig 68) ami bat (fig. 69) The same lettering and explanation does for all three. 



insects 



seen from above and from behind Tho ™«, i -, 7* ' ' 



w , ., . , ., , nd - lllc * m S s aie depressed in the direction of the arrows *, r, 



towanb th body, the straight lines representing the strings of the kites. The tendency of the 



1 hiiilf 1 Z f " ° f ^ amnVS * *' ^ as they are inclined obliquely from 



behind forwards, they meet and oppose each other in th, W J. „, ^ u~,„ «J w« the 



Fhr. 72 



fi 



body 



T>* ' '*• 



l°e7fr„m Io r c " Fly \ M r d r stka) ' dso ***** <° ^ «• **->*« -*- ° f ^ ^ 



SjTiTJS^ri* T " ^ ~ *°™S " -presented as striking *~ 



/ 



the 



