THE LEAF. 35 



EXERCISE X. 

 Forms of Sinuses. 



The SI'NUS of a leaf is the space left between lobes. 



We represent here some of the most usual forms 

 presented by Sinuses, with the terms describing them 

 printed below the pictures. 



FIG. 49. 



FIG. 50. 



FIG. 51. 



Sharp and deep Sinus. 



Broad, round, ehallovr Sinus. 



