12 GENERAL ORISMOLOGY. 



SUPERIOR SURFACE (superficies externa), the INFERIOR SURFACE 

 (sup. internd), the centre of the superior surface or DISC (discus), the 

 border surrounding the disc or LIMB (limbus). 



ANGLE (angulus), is that portion where two parts or the margins of 

 one meet ; SINUS (sinus), is a curved break in an otherwise straight 

 margin; KEEL (carina), is a sharp, longitudinal, gradually rising 

 elevation upon the inferior surface. 



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Besides these general definitions, which may be applied to all or very 

 many organs, the differences of form may be contemplated under the 

 following heads : 



1. Differences of Surface. 

 2. Differences of Solids. 

 3. Differences of Margin. 

 4. Differences of Apex. 

 5. Differences of Base. 



18. 



Figure of the Superficies. 



CIRCULAR (rotundum, circulare), is a round surface with its diameter 

 equal on all sides. 



ROUNDED (rotundate), when the margins pass gradually into each 

 other, and not meeting in sharp angles. 



OVAL (ovale), a rounded surface, its two right angular diameters 

 being of an unequal length, so that its longest transverse diameter does 

 not pass through the middle of its longitudinal diameter, but lies 

 nearer to one end. 



ELLIPTICAL (ellipticum), allied to the preceding, but differing, inas- 

 much as that its greatest transverse diameter passes through the centre 

 of the longitudinal. 



LANCEOLATE (lanceolatum), when the base is not so broad as the 

 centre, and the lateral margins slightly, but equally, swollen, gradually 

 tapering towards the apex, where it terminates in a point, and the 

 longitudinal diameter more than three times the length of the transverse. 



LINEAR (lineare), a figure having the lateral margins very close 

 together, and parallel throughout. 



HALF-.MOON SHAPED (lunare), a figure formed by the portion of a 

 circle cut off by the segment of a larger circle. 



