Notes . 
1 18 
pas proprement radicales ; 2° par l’existence des deux genres de 
coques qu’on trouve dans plusieurs lycopodes, savoir, les coques a 
poussiere et les coques qui portent des globules chagrinds et munis 
de trois cotes rayonnantes a leur base.’ In this he is followed by 
Brongniart 1 . Endlicher 2 , recognising the affinity between Isoetes 
and the Lycopodiaceae, does not, however, unite them, but founds 
the class Selagines which includes the two orders Lycopodiaceae 
and Isoeteae. The attitude of Lindley on this point is curious. 
In his Natural System of Botany (Ed. 2, 1836) he follows De Candolle 
in including Isoetes in the Lycopodiaceae, founding at the same 
time the cohort Lycopodales, consisting of the orders Lycopodiaceae, 
Marsiliaceae, and Salviniaceae ; whereas in his later works (Vege- 
table Kingdom, Ed. 2, 1846, Ed. 3, 1853), he removes Isoetes from 
the Lycopodiaceae and places it, with Marsilia, Pilularia , Salvima , 
and Azolla, in an order Marsiliaceae. Payer 3 retains Isoetes in 
the Lycopodiaceae, uniting it with Psilotum and Tmesipteris in the 
group Psiloteae. Berkeley 4 says with regard to it, ‘ on the whole, 
therefore, notwithstanding the difference in tissue, it should seem 
that it is a true Lycopod.’ 
The next important step in the classification of the Vascular 
Cryptogams was made by Sachs. Recognising the importance of 
distinguishing the homosporous (or isosporous) from the heterosporous 
forms, and at the same time overestimating it, in the three earlier 
editions of his Lehrbuch, he divides the Vascular Cryptogams into 
two groups, the isosporous, containing Filices, Equisetaceae, Ophio- 
glosseae, and the heterosporous, containing the Rhizocarpae and 
the Lycopodiaceae, pointing out at the same time that, among the 
Lycopodiaceae, heterospory only occurs in the Selaginelleae and 
Isoeteae. The fourth edition of the Lehrbuch 5 (1874) shows a 
marked advance. The classification here adopted brings to light 
the appreciation of the fact that heterospory has arisen within the 
limits of the several groups, each group (ex. Equisetaceae) therefore 
including both heterosporous and homosporous forms; the Rhizo- 
carpae are recognised as the heterosporous forms of the Fern-alliance, 
1 Ad. Brongniart, in Diet. Classique d’Hist. Nat. t. ix, 1826. 
2 Endlicher, Genera Plantarum, 1836-40. 
3 Payer, Botanique Cryptogamique, 1850. 
4 Berkeley, Introduction to Cryptogamic Botany, 1857. 
5 English edition, Oxford, 1882. 
