2S 



NOMENCLATURE. 



Pyramidal {pyramidatus, pyramidalis), when the section 

 of the body is angular, its apex tapering, and its base trun- 

 cated. A variety of this is the mitre-shaped {mitrtBformis)y 

 resembling a night-cap ; which form is very common in the 

 calyptrae of Mosses, and is opposed to the obliquely-cut form, 

 (calyptra dimidiata). 



31. 



We are also accustomed to derive the appellations of bodies 

 from their resemblance to various substances. Hence the 

 rule, That objects, either natural or artificial, which are sel- 

 dom met with, or, at least, which are not universally known, 

 ought not to be employed in comparing bodies. The most 

 usual expressions scarcely need any more particular explana- 

 tion. 



Mammillated (mammillatus), is commonly a hemispherical 

 body, with a small wart upon its top. 



Urceolate (urceolatus), when the body is expanded at both 

 ends, and contracted in the middle. (Tab. II. Fig. 16. Tab. 

 III. Fig. 12.) 



Cotyloid (cotT/loideus), when the body is depressed in the 

 centre, and elevated at the margin. (Tab. V. Fig. 12.) A 

 slighter degree of this figure is called saucer-shaped {scutelli- 

 formis)^ a higher degree cup-shaped {scyphiformis)^ or cupola- 

 shaped (cupulatus). When the surface is scarcely concave, 

 it is called plate-shaped (patdliformis). This passes into the 

 disc-shaped (disciformis). 



Lenticular (lenticularis), is a body depressed both on the 

 upper and lower surface, and of which the circumference is 

 round. This is called sMeld-sliaped, when the upper surface 

 is raised, and the lower somewhat hollow. The higher degree 

 of the shield-shaped passes into the meniscoid {meniscoideus). 



The spiral form {trochlear is) ^ resembles a screw, as in the 

 capsules of Helicteres. (See Spiralis^ § 37.) 



Spindle-shaped (fusiformis)^ is the conical form reversed, 

 with the lower end drawn out into a fine tapering form. But 

 we must distinguish this from Jusinus, which denotes a cy- 

 linder, which tapers at both ends. (Tab. 1. Fig. 31.) 



