Il8 SMITHSONIAN MISCELLANEOUS COLLECTIONS [vol. 50 



leaves, and at another more or less profoundly lobed and cut leaves. 

 There is of course abundant precedent for this condition among 

 living ferns and dicotyledons, but I am free to confess that the evi- 

 dence thus far presented does not seem to my mind sufficiently con- 

 clusive to warrant this sweeping contention, and I prefer to hold 

 with Seward, that "it is convenient to retain the name Protorhipis 

 for certain species of Wealden and Jurassic ferns," especially for 

 some of the smaller entire or dentate-margined forms, which do not 

 appear to have been cut or lobed after the manner of normal Dipteris 

 fronds. With imperfect or fragmentary material, it may sometimes 

 be difficult to distinguish between Protorhipis and Hausmannia, 

 and the possibility that the generic distinctness does not exist is ad- 

 mitted; but with good material it should not be so. Although the 

 nervation seems the same in both Andrae's and Zeiller's specimens 

 from Steierdorf, judging from the figures given by both authors, it 

 does not seem to me that it has been established beyond all doubt 

 that they come from the same plant. 



The question now comes as to the position of what I have here 

 called Protorhipis Ushcri. In size and shape it approaches most 

 closely to P. asarifolia Zigno, P. reniformis Heer, and P. cordata 

 Heer, but it seems to be extremely doubtful if either of these species 

 has anything to do with Protorhipis as founded byAndrae, as M611er r 

 Nathorst, and others have suggested. Indeed, Nathorst thinks it 

 probable that Heer's P. reniformis is a scale, possibly of some species 

 of Zamiostrobus, and the same may apparently be said of the others. 

 The nervation in the three forms above mentioned, when it can be 

 made out, is quite unlike that of typical P. biichii. The nervation of 

 P. Usheri, on the other hand, is of the same character as that shown 

 in the type of P. biichii, the main veins being several times forked 

 and the intermediate areas filled with a strong quadrangular areola- 

 tion. Unfortunately it is impossible to determine the character of 

 the margin in P. Ushcri, but it could hardly have been more than den- 

 tate, and there is certainly no evidence to show that it could be a por- 

 tion of a deeply bilobed or cut leaf. It may be necessary to establish 

 a new genus for the leaves under consideration, in the event that 

 the typical forms of Protorhipis are incontestably proved to be in- 

 distinguishable from Hausmannia. 



It further remains to consider the systematic position of the leaves 

 here called Protorhipis. As already indicated, Protorhipis bnclu'i 

 was placed by Andrae among the ferns, on the ground of its resem- 

 blance to certain forms of the younger fronds of the living Platy- 

 cerium. When the striking resemblance between this species and 



