Pteridophyten. 371 



externally b}^ phloem, but the latter does not occur at the corners 

 of the bündle; the condition in Diacalpe is not stated. In both plants 

 the leaf trace consists of several bundles at its departure from the 

 stele; it possesses three main bundles, two at the adaxial corners 

 of the petiole and one median abaxial one; between these Strands 

 are other smaller ones, sometimes as many as four or five. This 

 type of leaf trace seems to have originated in the phylogeny by the 

 breaking up of a Single horseshoe-shaped Strand. In the more pri- 

 mitive types, such as Lomaria, the leaf bundles seem to have been 

 inserted at the base of the gap; in Peranema and Diacalpe the 

 insertion of the Strands of the leaf seems to have become extended 

 over the sides of the lower half of the gap, while in Nephrodium 

 the region of their insertion extends also to the Upper half of 

 the gap. 



The sorus ol Peranema is of the mixed type but this plant 

 retains a receptacle which is suggestive rather of the Gradatae. In 

 Diacalpe the sorus is typical of the mixed type, but the annulus is 

 slightly oblique. 



On the whole Peranema and Diacalpe seem to be intermediate 

 "between the Cyatheaceae and certain phyla of Polypodiaceous cha- 

 racter". The two genera are clearly closely related and seem to fall 

 into the Woodsia-Woodsiineae group of the Polypodiaceae ; they are 

 certainly closely related to Nephrodium. 



Isabel Browne (University College London). 



Lang, W. H., On the Interpretation of the Vascular Ana- 

 tom v of the Ophioglossaceae. (Mem. Proc. Manchester Liter, 

 and Phil. Soc. LVI. Part. IL N°. 12. 1912.) 



In Botrychiiun and Helminthostachys the xylem at the base of 

 the sporeling is centrarch (i. e. the protoxylem is central and all the 

 wood centrifugal); the xylem raay be solid though parenchymatous 

 cells are usually mixed with the tracheides and if they are numerous 

 there may be a small pith from the first. In any case a medullated 

 stage is attained, the protoxylem being at first on the inner margin 

 of the xylem. In Helminthostachys, however, centripetal xylem soon 

 appears; the wood thus becomes mesarch and remains so in the 

 mature rhizomes. In this genus there is usually no secondary xylem , 

 but in branched rhizomes accessory wood comparable to secondary 

 xylem develops between the phloem and xylem either at the insertion 

 of the branch or all round the stele for a little distance above and 

 below the branch. In Botrychium the phase in which the xylem 

 consists of an endarch medullated cylinder persists long; later scat- 

 tered obviously centripetal tracheides may develop in the pith ; 

 groups of other tracheides also develop close to the X3 r lem cilinder, 

 but it is doubtfull if these are centripetal. Secondary xylem, which 

 it is often impossible to distinguish sharply from the primary cen- 

 trifugal wood is produced. In Ophioglossum there is no secondary 

 xylem and the leaf gaps in the stele overlap; usually only centri- 

 fugal xylem is found, but in a species from Ceylon in which the 

 stem bore two branches and was itself arrested scattered centri- 

 petal tracheides were found in the pith. 



The occurrence of an internal endodermis is very irregulär in 

 the family; it seems to reach its greatest development in certain 

 species of Botrychium; it has been thought that the fact that in 

 these species and in certain species of Ophioglossum it may be 



