— 427 — 
Phyllotheca Muelleriana n. sp. 
Pl V, Fig. 8. 
Leaves delicate, a little lax, linear, united for about 5mm. to 
7mm. atthe base,to form an erect sheath, and abruptly arched out- 
ward at the top of the sheath to assume avery open or nearly hori- 
aontal position fora short distance, then turning upward to nearly 
vertical for the greater part of their length, the rather obtuse apices 
being often somewhat sharply inward hooked; sheath narrow and ere- 
ct for about two thirds or more ofits length, then very rapidly ope- 
ning outward to the point of fission; medium nerve distinct, about one 
fourth the width of the lamina through the middle portion of the 
leaf. 
This very interesting equisetal type is represented by but a single 
specimen which, as shown in Pl. V, Fig. 8, contains portions of 
nine detached verticils. The orientation of these on the rock indicates 
a probable common derivation from a single individual plant. All 
the material is slightly macerated, and no definite trace of the parent 
Stem is seen. 
The essential characters of the species are the abrupt dilation of 
the sheath at the top, the strong outward arching of the leaves for some 
distance beyond thesheath to form a cup about three or four times 
the width of theerect portion of the sheath; and the subsequent as- 
sumption of an erect position. The incurving of the apical portions 
observed in most of the leaves seems far too uniform and well marked 
to be ascribed to wilting or the mere accident of perservation. In some 
instances the top of the leaf is inrolled like the circinnate vernation 
of a fern. 
The aspect of the verticils is at first glance suggestive of an 
enormous Calymmatotheca, or of a Beinertia. 
The Gondwana species that appear most nearly related to Phyl- 
lotheca Muelleriana are Piyllotheca Griesbachi and Pyllotheca indica. 
By the general attitude, aswell as by the outward and subsequent 
upward curve of the leaves our plant somewhat resembles Phyllotheca 
Griesbacii, though the shape of the cupcorresponds only ina minor 
degree, 
On the other hand the erect form of the smaller verticils of 
Phyllotheca indica and Phyllotheca australis; but the dilation of the 
upper portion of the sheath seems to differ from that of Phyllotheca 
