2CJS DR. PETTIGREW ON THE MECHANISM OF FLIGHT. 



Fig. 2. The Common Otter (Lutra vulgaris), adapted for land and water. 



1 {. The Onuthorhynchus {Ornithorfujnchus paradoxus, Blum.), adapted likewise for land and water, 



the extremities being more expanded than in the Otter. 

 Fig. 4. The Bed (Phoca fmtida, Midi), adapted principally for water, the extremities being larger than 



in cither of the foregoing. 



'nun 



diving. 



Ho 



with tok'i 



both in ai 



It also walks 

 ;s movements. 



Kg. 7. The Turtle (Chelonia imbricata) , adapted for swimming and diving, the extremities being relatively 



larger than in any of the preceding, 

 lig. 8. The Crested Newt {Triton cristatus, Laur.). In this a tail is superadded to the extremities, the 



tail and the extremities both acting in swimming. 

 he Manatee (Manatus americanus) . Here the t; 

 anterior extremities being rudimentary and small 



prm 



Tig. 10. The Porpoise (Phocama communis). The anterior extremities of the Porpoise are more rudi- 

 mentary and finlike than those of the Manatee, the tail and under part of the body being finely 

 moulded, and chiefly engaged in locomotion. The Manatee and Dolphin strike the water from 

 above downwards or vertically ; and in this respect they differ from the newt and fish, which 

 strike it laterally or from side to side. 



Fig. 11. The Snlmon (Salmo salar). In this the extremities have disappeared, the travelling-power 



residing in the lower half of the body and greatly expanded tail. If the lower part of the body 

 aud tail be compared with the feet of the ox (fig. 1), the increase of surface engaged in loco- 

 motion becomes very evident. 



Fig. 12. The Flyingfish (Exoccetus exsiliens, Linn.). Here the creature is adapted both for swimming 



and flying. The swimming-tail is consequently retained, and the pectoral fins, which act as 

 wings, are enormously increased in size. The pectoral fins are not sufficiently large to support 

 the fish permanently in the air. They, however, do this very efficiently for short periods. The 

 Flyingfish may be regarded as forming one of the connecting links between the water and the 

 air, the heavy-bodied short-winged swimming and diving birds forming the other. The wing 

 of the Flyingfish is elevated and rotated in an outward direction at one and the same time; 

 so that it strikes the air from beneath, as a boy's kite would. 



Plate XIII. 



Fig. 13. The Red-throated Dragon (Draco hamatopogon, Gray) shows a large membranous expansion (a b) 



situated between the anterior and posterior extremities and supported by the ribs. The Dragon 



by this arrangement can take extensive leaps with perfect safety. 





Fig. 1 1 . Alucita hexadactyla (from Dallas) . 



filaments or winglets, which in flight act like cilia. 



insect 



like the feathers of the wing in 



urface 

 They 



this respect from the wings of the bat and those of insects generally. When the insect is 



Fig 



reposing they fold up like a fan. 



elling-surface (r def, 



To? W TT ° f the ^ "* ^^^ generally It, moreover, gre* 



ex eeds hat found >n rnany of the insects (fig. 16) and birds (p f ate ^ ^ 



! , , ? { t" 9mma Cen ' mrm) - Seen from abOT e. Shows two pair* of elytra (r), 



and two pa lrs of membranous wings W m the exteaded stafe ^ ' ^ „d 



