124 DICTYOrHYLLUM. 



as regards the form of the frond, with Matonia pectinata, R. Br., 

 but the soral characters and the form of the leaf point rather 

 to a comparison with the genus Dipteris. Dipteris l is a tropical 

 Indo-Malay type represented at the present day by a few species, 

 which have usually been placed among the Polypodiacese, but the 

 sporangia do not appear to be typically polypodiaceous, and the 

 rgenus is clearly an isolated type of somewhat uncertain position. 

 Raciborski 2 has suggested the new family term Protopolypodiacete 

 for the reception of a fertile Dictyophyllum leaf characterized by 

 naked sori, consisting of a few sporangia with an oblique annulus, 

 characters which are found also in the recent species of Dipteris. 

 It is proposed to discuss more fully elsewhere the systematic 

 position of the recent genus, but such evidence as we at present 

 possess favours the view that Dictyophyllum and Protorhipis are 

 closely related to Dipteris, and constitute Mesozoic members of 

 a group of ferns now barely represented, but in former times 

 widely distributed. It may be c6nvenient to emphasize the 

 affinity of Dictyophyllum with Dipteris, and the isolated position 

 of both these genera and. Protorhipis, by placing them provisionally 

 in a separate family, which we may designate the Dipteridinse, 

 using in a wider sense a term already employed with a more 

 restricted meaning. 



39,224. PI. XIII. Fig. 3. 



Portions of two pinnee which are so placed as to suggest their 

 proximity to a common rachis towards which they are converging. 

 The whole frond probably had a habit similar to that of Matonia 

 pectinata, Cheiropteris, Laccopteris, and other genera. The single 

 segment represented in the figure is given off practically at right 

 angles from the axis of the pinna, and represents a portion of 

 a long and narrow segment with irregularly dentate or undulating 

 margins, similar to the form of leaf named by Zigno Dictyophyllum 

 Leckenlyi. The venation characters are fairly well shown in the 

 figured specimen. Labelled Phlelopteris Phillipsii in Bean's MS. 



Gristhorpe. Sean Coll. 



1 Engler & Prantl (99), p. 202, fig. 108. Vide also Beddome (66), pi. Ixxx. 



2 Raciborski (91), p. 8. Vide also Potonie (99), p. 86. 



