There are a few fossil stems from Permian rocks of Siberia, from Jurassic strata in Italy, and from Lower Mesozoic and Permo-Carboniferous beds in South America, South Africa, India and Australia which do not conform in all points to the usually accepted definition of _Equisetites_, and so justify their inclusion in an allied genus. On the other hand there are numerous instances of stems or branches which have been referred to _Phyllotheca_ on insufficient grounds. Our knowledge of this Equisetaceous plant has recently been extended by Zeiller[549], who has recorded its occurrence in the Coal-Measures of Asia Minor associated with typical Upper Carboniferous plants. The same author[550] has also brought forward good evidence for the Permian age of the beds in Siberia and Altai, where _Phyllotheca_ has long been known. It is true that Zigno’s species of the genus occurs in Italian Jurassic rocks, but on the whole it would seem that this genus is rather a Permian than a Jurassic type. The species which Zeiller describes under the name _Phyllotheca Rallii_ from the Coal-Measures of Herakleion (Asia Minor) shows some points of contact with _Annularia_. It is much to be desired, however, that we might learn more as to the reproductive organs of this member of the Equisetales; until we possess a closer acquaintance with the fructification we cannot hope to arrive at any satisfactory conclusion as to the exact position of the genus among the Calamarian and Equisetaceous forms. M. Zeiller[551] informs me that his specimens of _P. Rallii_, which are to be fully described in a forthcoming work, include fossil strobili resembling those of _Annularia radiata_. The verticils of linear leaves fused basally into a sheath agree in appearance with the star-like leaves of _Annularia_, but in _Phyllotheca Rallii_ the segments appear to spread in all directions and are not extended in one plane as in the typical _Annularia_[552]. 1. _Phyllotheca deliquescens_ (Göpp.). In an account of some fossil plants collected by Tchikatcheff in Altai, Göppert[553] describes and figures two imperfect stems of an Equisetum-like plant. Owing to the apparent absence of nodal lines on the surface of the stem the generic name _Anarthrocanna_ is proposed for the fossils; and the manner in which the main axis appears to break up into slender branches suggested the specific name _deliquescens_. Schmalhausen[554] afterwards recognised the generic identity of Göppert’s fragments with the Indian and Australian stems referred to the genus _Phyllotheca_ by McCoy[555] and Bunbury[556]. We may define the species as follows:—