234 MESSRS, T. A, SPRAGUE AND J, HUTCHINSON ON 
pluribus, primaria oppositifolia, reliquis inter cymam primariam et petiolum 
ortis.— Lappula et Bartramea, DC. Prodr. i. 506 (1824). 
Species circiter 90, regionum calidiorum utriusque orbis incole. 
Before discussing the relative antiquity of the sections it will be con- 
venient to state what characters we regard as primitive in 7 riumfetta. 
1. Those commonly found in the Malvales or in Tiliaceæ : such are stellate 
hairs, palmate venation of the leaves, numerous stamens, and a several- 
celled ovary and fruit, relatively to simple hairs, pinnate venation, few 
stamens, and a 1-2-celled ovary and fruit. 
2. Those common to Triumfetta and certain other genera of Tiliaceæ : such 
are the subapical horns of the sepals, and the gonophore. 
8. A simple or little specialized as opposed to a complex or highly 
specialized inflorescence or fruit. 
4. Fruticose or suffruticose relatively to herbaceous habit. 
Further, we hold that a group with few, well-defined species may, ceteris 
paribus, be regarded as older than one including many ill-defined species ; 
also that a group with discontinuous distribution and species of restricted 
area may be held to be older than one with continuous distribution and 
widely spread species. 
Our ideas as to the relations between the four sections may be represented 
graphieally as follows :— EM 
Porpa - Lepidocalyx 
Ve ie E 
Lasiothrix Lappula 
On the top line are Porpa and Lepidocalyx, sections including only 2 species 
each, with numerous stamens and woody several-celled fruits. Porpa with 
simple inflorescence appears to represent a primitive type; whilst Lepido- 
calyx, which may be regarded аз highly archaic on account of the scaly 
calyx and spindle-shaped tubercles, presents in its inflorescence a type 
approaching to that of Lappula. 
Porpa and Lasiothrix on the left, and Lepidocalyx and Lappula on the 
right, have respectively a single cyme, and two or more cymes at each node. 
On the bottom line are Lasiothriz with 16 species, and Lappula with about 
90 species. In both the inflorescence is on the whole more modified, although 
of the same general type as in Porpa and Lepidocalyx respectively ; in both, 
besides species with numerous stamens, there are others with 10-12 stamens 
or fewer ; and in both, the fruit shows special modifications for distribution. 
For these reasons we regard Lasiothriv and Lappula as more modern 
