In order to emphasise the isolated position of the genus it has recently been placed in a separate family, the Matonineae, of which it is the sole living representative. The restricted geographical range of Matonia, considered in connexion with the clearly marked peculiarities in structure and form, leads us to expect other evidence in support of the natural inference that the genus is a survivor of a once more vigorous and widely spread family. If Matonia were a recently evolved type which has not spread far from its original home, we should expect it to conform more closely than it does to other ferns in the Malay region. Even assuming for the sake of argument that variation may occur _per saltum_, and new forms may be produced differing in more than the finer shades of small variation from their parents, the peculiar features of Matonia are too pronounced and its individual characteristics too obvious to warrant the assumption of recent production. It is, however, from the testimony of the rocks that we obtain confirmation of the opinion that these Malayan species are plants on the verge of extinction. In shales of Jurassic age exposed on the Yorkshire coast at Gristhorpe Bay and in iron-stained rocks of the same age between Whitby and Scarborough, well preserved leaves have been found agreeing in the shape of the frond, as also in the form of the leaflets and of the groups of sporangia which they bare, with those of _Matonia pectinata_. The exposure by a stroke of the hammer, on the fractured surface of a rock picked up on the beach at Hayburn Wyke (a few miles south of Whitby), of a piece of fern frond which is unmistakably closely allied to the species described by Wallace on Mount Ophir, establishes a link between the Jurassic and the present era and presents a fascinating problem in geographical distribution. These fossil Matonias are known to students of ancient plants as species of the genus Matonidium, a name adopted by a German botanist for specimens apparently identical with those from the Yorkshire coast discovered in slightly younger rocks (Wealden) in North Germany. The same type has been found also in sediments of Wealden age on the Sussex coast. Other leaf-impressions agreeing closely with those of Matonidium have been obtained from the Yorkshire Jurassic rocks and these are assigned to another genus Laccopteris, an extinct member of the family Matonineae. It is not merely in the habit of the fronds and in the shape and venation of the leaflets that these fossil ferns resemble the existing species, but the more important features exhibited by the spore-capsules supply additional evidence. It has already been pointed out that the stems of Matonia are characterised by a type of structure unknown in an identical form in any other recent fern.