PEOIOPTEEIS. 73 



Stenzel' has referred to several Protopteris species in his 

 important communication on Rhizodendron OppoUense, Goppert; 

 he points out that P. Cottai should be regarded as a synonym of 

 P. Cotteana, Presl, and refers the specimen described in 1865 by 

 Goppert '' as P. Sternhergii to a new species, P. fibrosa, Stenz. 



Protopteris Witteana, Schenk. 

 PL XI. 



The most important specimen of Protopteris Witteana from a 

 botanical point of view is represented in PI. XI. ; it is in all 

 probabUity from the English Wealden rocks, but unfortunately the 

 registered number is partly illegible, and cannot be identified with 

 any entry in the MSS. Catalogue of the Geological Collections. 



This piece of stem has probably been slightly compressed, and 

 the external surface suggests considerable rolling ; it tapers slightly 

 towards both of the bluntly rounded ends. The internal structure 

 is partially preserved, apparently in carbonate of lime, but the 

 details are very imperfectly shown in microscopic sections. On 

 the smooth water-worn surface the petiole bases are seen to be 

 broadly oval in form, and slightly projecting above the general 

 level of the stem ; in each leaf-scar the horse-shoe vascular bundle 

 is more or less clearly marked. Fig. 3, PI. XI.^ shows one of the 

 more perfect leaf-trace bundles at t, and external to this at s the 

 peripheral sclerenchymatous tissue of the petiole ; such a form 

 agrees more closely with that of Protopteris Witteana as figured 

 by Schenk, than with the more constricted form of P. punctata. 

 In the immediate neighbourhood of the leaf-trace there are a few 

 small circular markings, and occasionally these show two con- 

 centric circles, as at r.r. in Fig. 3 ; the inner no doubt representing 

 the vascular axis, and the outer the peripheral limits of an 

 adventitious root. In the same Figure at r'.r'. there are obHque 

 longitudinal sections of adventitious roots. In some of the leaf- 

 trace bundles it is possible to see clearly the peripheral stereome 

 tissue of the petiole base, which weathering agencies have 

 occasionally left in relief immediately above the upper end of 

 the vascular strand ; e.g. at «, Fig. 1 . 



There is a very striking resemblance between the more perfectly 



1 Jahres-Ber. Schles. Ges. Kultur, 1886. 



2 N. Jahrb. 1865, p. 395. 



3 This drawing is made from the ground-down surface of the specimen. 



