BERRY: FERN GENUS CLATHROPTERIS 281 
Cenozoic, generally estimated at several millions of years, during 
which it is almost inconceivable that family boundaries did not 
shift. At the same time there seems to be a consensus of opinion 
that the existing Dipteriaceae represent the last relics of this 
adaptive radiation of the Camptopteriaceae, so that the question 
of family nomenclature is really not of great importance. 
Specimens referable to Clathropteris and probably representing 
several botanical species, but not certainly distinguishable in the 
present state of our knowledge, have a very wide geographic and a 
very considerable geologic range. In this country they are found 
in the rocks of the Newark formation, probably of Keuper age, in 
Massachusetts, Connecticut, New Jersey and Virginia. They 
occur in the Keuper of Prussian Saxony and Switzerland. In the 
succeeding Rhaetic they are found in Sweden, Bornholm, Germany, 
France, England, Persia, China and Tonkin. In rocks referred 
to the lower Lias they are recorded from Hungary, Saxony, Silesia 
and France. Owing to the peculiar habit of these ferns and the 
often great length of the pinnae the specimens are usually much 
broken, the best foreign material probably being that described 
by Zeiller (op. cit.) from Tonkin. 
As regards the habit it appears that the dichotomously forked 
rhizomes described by Nathorst (op. cit.) as Rhizomopteris cruciata 
represent the rhizomes of Clathropteris. The scars on these 
rhizomes indicate that in the Swedish region the fronds were not 
as crowded as they were in the allied Dictyophyllum growing at the 
same locality. The Virginia material shows that the stipes were 
stout and somewhat curved (in this respect suggesting Mertensia), 
as much as a centimeter in diameter, and with a longitudinally 
striated epidermis. 
These stipes, rising for a considerable ditcare from the creeping 
rhizome, divided dichotomously at a wide angle and bore on the 
upper side of this fork from ten to thirty pinnae as in the genera 
Dictyophyllum and Camptopteris, species of both of which genera 
have been admirably restored by Nathorst. These pinnae are 
said to be fused proximad but it may be considered certain that 
the amount or absence of fusion was a variable feature as it is 
demonstrated to have been in the allied genus Dictyophyllum. 
It appears from Zeiller’s Tonkin material that these primary pinnae 
