XXVl] SAGENOPTERIS 477 



The lebes of the pinnules are incurved distally to form a 

 capsule, containing four sporangia, which apparently opened on 

 dehiscence into four valves; the spores are of one size. The 

 material is however insufficient for accurate determination. 



There is no evidence contributed by fossil records which 

 indicates a high antiquity for the Hydropterideae. It is unsafe 

 to base any coliclusion on the absence of undoubted Palaeozoic 

 representatives of this group ; but the almost complete absence 

 of records in pre-Tertiary strata is a fact which may be allowed 

 some weight in regard to the possible evolution of the hetero- 

 sporous filicales at a comparatively late period in the earth's 

 history. 



A description of the Mesozoic genus Sagenopteris may be 

 conveniently included in this chapter, though as in many other 

 instances the inclusion of a genus under the heading of a recent 

 family name does not by any means imply that the position of 

 the extinct type is regarded as settled. 



Sagenopteris. 



This generic name was applied by Presl^ to small fronds 

 composed of four or rarely two palmately disposed leaflets with 

 a more or less distinct midrib and anastomosing secondary 

 veins. Schimper^ compared Sagenopteris with Marsilia, but 

 did not regard the resemblance as evidence of relationship. 

 Nathorst' expressed the opinion that certain fruit-like bodies 

 obtained from the Rhaetic beds of Scania are of the nature of 

 sporocarps and were borne by Sagenopteris, with the leaves of 

 which they were associated. He published a drawing of part of 

 a fruit showing on its partially flattened surface some raised 

 oval bodies which are considered to be spores. Dr Nathorst 

 kindly placed at my disposal the drawings reproduced in 

 fig. 325 made from some of his specimens found at Bjuf in 

 Scania. 



In contour and superficial features, e.g. the veining on 

 the wall, these bodies bear a fairly close resemblance to the 



1 Presl, in Sternberg (38) A. ^ Schimper (69) A. ^ Nathorst (78) p. 17. 



