Foil FOllM^ AND QUALITIES, 



The surface (pagma) is the extension of a part, and is 

 commonly divided into the upper and under surface. 



The margin {mar go) is the boundary which unites the two 

 surfaces. In a more common sense, when any thing is car- 

 ried from the sides to this part, it is called the circumference 

 or ray {ambitus^ radius). That which lies in the circumfe- 

 rence is called radialis or periphericus, (Tab. I. Fig. SO.) 

 When the margin is perceptibly distinguished by its sub- 

 stance or colour from the central part or disc, the organ is 

 said to be marginated (margmatus), as the leaves of Saxifra- 

 ga aizoon, Bryvim marginatum, and the fruits of many of the 

 lichens, (22.) 



Limitate (limitatu^), is, w-hen the boundary is sharply 

 marked ; as, for instance, in Lecideu geog raphica, parasema^ 

 and others. 



The opposite of Umitatus is expressed by effusus, {Stroma 

 SphfEVia, serpentis.) 



The central part of the surface, in opposition to the cir- 

 cumference, is denominated the disc^ (discus). But this word 

 is used equally with respect to leaves and flowers. 



The limb (limbus, or lamina), is used with respect to the 

 extended surfaces of flowers ; the former term, when the co- 

 rolla consists of but one petal, the latter, of more than one. 



The Jceel {carina), is the prominent line or ridge on the 

 under side of a horizontal surface. 



Angle (angulus), is the point where two lines or surfaces 

 meet one another. It is hence applicable as well to the cir- 

 cumference of the leaves as to the stem and stalk. 



The sinus, means the curvilineal indentation between two 

 projecting angles. It is chiefly used with respect to the mar- 

 gins of the leaves. 



Umbilicus, is a depressed surface, surrounded by an ele- 

 vated margin. 



Appendage {apophysis), is a smaller body attached to a 

 greater, which, in the capsules of the Mosses, ]jconmionly 

 called the crop, {struma). 



