33 



ELEMENTARY ZOOLOGY. 



large water birds in which all four of the toes are united 

 by the web. They are heavy eaters, living chiefly on 

 fish. They are expert fishermen the white pelicans 



FIG. 137. Ross" gull (Rhodostethia rosea). Upper figure adult male; lower, young 

 female. From "Chapters on Natural History," Shufeldt. 



Questions on the Figure. What indications of structural adap- 

 tation to habits do you find in the figure? What differences do you 

 find in the sexes? 



even fishing together and driving their prey before them 

 into shallow water, where they capture numbers of them 

 in the pouch of the lower jaw (Fig. 139) . 



