Paper ii and A ha tracts. ' 53 



The iiKJst important character that sliows any cuiisideiablc variation m the 

 hving species (apart from Oiiiminda riniwinomea) is the extent of the interruption 

 m the continuity of the xylem ring caused by the departure of the, leaf-traces. 

 Osmunda regaHs represents one extreme, where the xylem ring is broken up into 

 many distinct strands free from one another, while the other extreme is shown 

 by Tod,ea barbara and T. .■aujjcrba, in which the strands are fused with each other 

 and with the xylem ()t' the leaf-trace, so forming continuous bands. As regards 

 the two fossil species, Osmunditcs Duiilojji, with its continuous xylem ring, 

 points in the direction of Todca barbara, while 0. Gibblana points in" the direc- 

 tion of 0. regalis. and the authois consider that amongst the living Osinundaceae, 

 "so far as our data permit us to judge," 7'. barbara shows most resemblance to 

 O. Daidopi, and O. regalis to O. (iibbiana. But until the sporophylls are known 

 the species are to be kept in the fossil genus Osiniiiidifni. 



An unnamed Oannindites in the British Museum collection, said to have come 

 from New Zealand, was examined, and was found identical with O. Diiidopi. 



Besides the two species mentioned above, ail the recorded fossils of an osmiuid- 

 accous charactei' are dealt with excepting one. A table is given showing th<: 

 chronological order of the species, and a synopsis of their more important ana- 

 tomical features. This latter shows that the medullation of the stele and the 

 subse(juent breaking-up of the xylem ring takes place pari imishi with the advance 

 from the older to the younger strata. The age of the fossils is as follows : 

 Upper Permian, ') : Jurassic, '1 ; Upper .Jurassic, 1; Lower Cretaceous, 1; i^ower 

 Eocene, 1 ; i^ower Pliocene or Upper Miocene, 1. 



Dealing with the ancestry of the O.-^inundacfac-, the authors consider them, as 

 a whole, as "an ascending series of forms whose vascular system is to be derived 

 from a primitive protostele with a solid homogeneous xylem," by the medulla- 

 tion of which and the subsequent breaking-up of the peripheral xylem ring thus 

 formed into separate strands the typical osmundaceous stele has been derived. 



By a consideration of the methods through which the medullation of the 

 stele has come about, the authors find the existence of an intermediate stage in 

 which the pith consists of tracheae mixed with parenchyma, and it becomes 

 inevitable that the mixed pith of the Zygopte.rideae. is of the same nature and 

 origin as that of the Osinundaceae, especially as the authors believe the two 

 families have descended from a common ancestor. Further, the authors postulate 

 the discovery of a primitive zygopterid stele with a solid xylem mass, the central 

 tracheae of which are short, and transitional toward a pith, as in two of the 

 osmundaceous genera dealt with. 



This prophecy was confirmed by the discovery of a stele exactly as antici- 

 pated by W. T. Gordon, a figure of which is given. 



The monograph concludes with an attempt to explain the derivation of the 

 .specialized leaf-trace of the Zygopterideac from the simple primitive form of the 

 Osinundaceae. L. C. 



6. The Morphology of^,, the Podocarpineae. By Mary S. Young. 

 (Bofa/iicai Gazette, vol. ."JU, pp. 81-lUU, pis. 4-6. August, 1910.) 



Before the year 1902 very little was known regarding the morphology of 

 the Podocarpinaceae, but since that date a number of investigators, using in large 

 part material from New Zealand, have found out a good deal about the group, 

 the only genus yet untouched being Pherosphaera, with its two species. Of special 

 interest is the question of relationships of the Podocarpineae, particularly with 

 regard to the Araucarineae. 



The paper deals first with the gametophytes of Phyllocladus, the authoress 

 having examined a considerable amount of material of Phyllocladus alpinu-?, 

 which had been collected by the reviewer at fairly regular intervals from the 

 16th October to the 28th January. A full account is given of the male and female 

 gametophytes, and of the process of fertilization, and there is something as to 

 the development of the embryo. The conclusion come to by the authoress regard- 

 ing the affinities of Phyllocladus is that it is a relatively primitive member of the 

 Podocarpineae, which branched off from them a comparatively short time after 

 their separation from the Taxineae. This conclusion is based on the following : 

 (1) Phyllocladus has primitive characters of the Taxineae which are being elimi- 

 nated in the Podocarj)i>icae ; (2) it has primitive characters of the Podocarpineae 

 which have been entirely eliminated in the Taxineae; (3) it has some advanceed 

 characters of Podocarpineae; (4) the taxad resemblances are more superficial and 

 variable, and the podocarp features more fundamental. 



