42 TlMEHRI. 
the Calamites, Lepidodendrons and other fossil genera 
of the coal measures attest. 
Key to the Arrangement. 
Series I. — Spores all of one kind. — Microspores. 
Order I. — Lycopodiacece. 
,, II. — Equisetacece. 
Series 11. — Spores of two different kinds. — Microspores and Macro- 
spores. 
Order I. — Selaginillacece. 
,, II. — Marsileacece*. 
„ III. — Salviniacece. 
Series I. 
Order I.— Lycopodiaoea. 
Stems ere£t prostrate or pendent, with terete or flattened branches, 
which are more or less repeatedly dichotomous (except in Phylloglos- 
sum), and leafy throughout. Leaves relatively small, often minute, 
simple or forked, one-nerved, many-seried and irregularly whorled, or, 
rarely, distichous ; usually linear or subulate, close and imbricating or 
more apart, rarely distant. Sporangia bi- or tri-valved, single, sessile 
and axillary in the leaves of the normal or modified branches, or in 
special spikes. Spores of one kind, abundant and dust-like. 
Four genera, comprise this order, but only two of them 
are represented in Guiana. The others — Phylloglossum 
and Tmesepteris — are confined almost entirely to Aus- 
tralia and the adjacent islands, Tmesepteris reaching to 
California. 
Genus I.— Lycopodlum. Linn. 
Sporangia reniform, one-celled, bivalved, axillary in the normal or 
modified leaves of the outer parts of the branches, or in the imbricating 
scales of special spikes. Leaves of one or two kinds, multifarious, rarely 
distichous or biserial, generally close and often imbricating. Stems and 
branches mostly terete, dichotomously or pinnately branched, leafy 
throughout. 
These are the true club-mosses, and their aspect, except 
in a few instances, is very different from that of their aJlies 
the Selaginellas, from which they are technically distin- 
guished by having only one kind of spores and spore-cap- 
