156 AN INTRODUCTION 
tification that can be relied on asa conftant 
characteriflic Mark for all Genera ; it being 
found, that the Part which is conftant in 
fome Genera will be inconftant in others: 
Thus in Carica the Flowers of the male 
Plant are monopetalous, and thofe of the fe- 
male pentapetalous ; in Myrica fome Species 
have naked Seeds, others Berries ; in Fraxi- 
nus fome have a naked Flower, and others a 
Corolla; in Geranium fome have regular 
Corolle, and others irregular; in Linum 
fome are pentapetalous, others tetrapetalous ; ” 
in Aconitum fome are tricapfular, and others 
quinquecapfular ; and in Trifolium fome are 
monopetalous, others polypetalous, fome 
monofpermous, and others polyfpermous. 
This Inconflancy of particular Parts in 
many Genera has_ been another Source of 
Error among{t the earlier Botanifts ; who 
have parted many Plants from their Conge- 
ners on this Account: Of thefe Miftakes 
we fhall give an ample Lift in Chapter 32. 
When the characteriftic Mark of any 
Genus is wanting in any particular Species, 
we fhould proceed with Caution, left we 
confound Genera that fhould be diftinguith- 
ed : For want of this Caution the Erica and 
Andromeda had been joined, but were parted 
afterwards on Account of the two Horns in 
s 7 the 
