Copeland . — The Mechanism of Stomata. 355 
with the hinge back of the guard-cell ; and the line where 
dorsal and inner walls meet thickened to the end. 
Viola ovata , Nutt. Achillea type. 
Viola blanda , Willd., var. palustriformis , Gray. Achillea 
type, but thickened less than typical. 
Claytonia Caroliniana , Mx. Medeola type ; surface view 
almost round ; in contact with several cells. 
Er odium cicutarium. Helleborus type. 
Anemonella thalictroides , Spach. Medeola type, in spite of 
thickened walls ; ends and sides of guard-cells locally rein- 
forced. 
Caltha palustris , L. Slightly flatter than Anthoceros (Fig. 
53) in cross-section, very large. 
Delphinium tricorne, Mx. Amaryllis type. 
A coni turn uncinatum , L. Achillea type. 
Caulophyllum thalictroides , Mx. Helleborus type. 
Capsella bursa-pas toris, Moench, Helleborus type, narrow. 
Dentaria diphylla , Mx. Like Capsella , but less thickened. 
Both of these Cruciferae are about as near Achillea as Helle- 
borus. 
Desmodium Dillenii , Dari. Narrow: Amaryllis or Sagit - 
iaria type on leaf, with subsidiary cells. 
Cassia Marilandica , L. Like Desmodium . Stem without 
stomata. 
Geum vernum , L. Helleborus type, dorsal walls quite 
oblique. 
Saxifraga Virginica, Mx. Nearest Amaryllis', but inner 
wall thicker than outer. 
Chrysosplenium Americanum , Schwein. Medeola type, with 
suggestion of Amaryllis ; sometimes angular, 
Liquidambar Styraciflua , L. Like type of the Gramineae 
in the depth of the subsidiary cells ; and thin ends of guard- 
cells very evident in surface view. In median cross-section 
like Achillea. 
Hamamelis Virginiana , L. Like Liquidambar , but more 
thickened. 
Cuphea viscosissima , Jacq. Helleborus type. 
