No. 476] 



VOLA \ T A DA PTA TIONS 



541 



their base, while distally each ray bifurcates to give more support 

 to the flying membrane. The lengthening of the pectoral fins 

 varies with the species, being greatest in those with the best powers 

 of flight. 



The bodily contour seems to liave suiiVnMl but little alt.M-ation 

 due to the drvdopuuMit of fliu^lit. Tlir lower lob,- of tlir < aii.lal 

 fin is much tlu> lonu-.-r and thus becnnics more cllicic-iit in -iviiiu- 

 the n^h its final impetus upon l.'a\iiii: tli<' uaU'r. It i. aUu .aid 

 that the fin is occasionally subincruvd .luriiio- Hiulu ami ai(l> in 

 changing the direction of the fisli. 



Nearly all of the Scombresoci.hr. to uliidi t'aniily this Hyiii^- 

 fish belongs, have tlie j)o\vcr of takinu' urt'at leaps out of the water, 

 culminating in Exoc(X'tiis. In the developinciu of the pectoral fin 



bresox to Exoc(rtus, Ilemiexocu'tiis bcino- a v(>ry remarkable con- 

 necting form fBoulenger). 



Exocoetus is tropical to subtroj)i( al in ilisiribution. some species 



