u8 



NA TURE 



[June i, 1882 



In seme of the new specimens the vasculo-medullary axes 

 present no differences from those of the Astromyelon already 

 described. The radiating lines of cells separating the lamirue 

 prove to be transverse sections of elongated vertical laminae 

 composed of cells with a mural arrangement, and which separate 

 large vertical lacunae of varying lengths ; a type of cortical 

 ti'sue clearly indicating a plant of aquatic habits. So far as 

 this bark is concerned, all the ramifications of the plant display 

 similar features, but several of the specimens exhibit important 

 variations in the structure of the vasculo-medullary axis. In 

 them the central cellular medulla is replaced by an axial va cular 

 bundle, which has little, or in some examples apparently no, 

 cellular element intermingled with the vascular portions. In 

 some examples this axial bundle is invested by the thick exoge- 

 nous zone seen in Astromyelon. In others that zone is wholly 

 wanting. Yet there appears to be no reaon for doubting that 

 these are but varied states of the same plant which branched 

 freely, the differentiated branches having, doubtless, some mor- 

 phological significances, as yet incapable of being explained. 

 That the plant was a Phanerogam allied to Myriophyllum, is 

 most improbable. It has several features of resemblance to 

 the Cryptogamic Marsilea?, frem which it does not differ more 

 widely than the fossil Lepidodendra do from the living I.yco- 

 podiaceae. 



The author describes a new specimen of Fsaronius Rtnaullii, 

 found by Mr. Wild, of Ashton-under-Lyne. Those previously 

 described, consisted almost entirely of fragments of the bark 

 and its aerial rootlets. The present specimen contains a perfect 

 C-shaped fibro-vascular bundle and a portion of a second one, 

 resembling some of those described by Corda, and which leave 

 no room for doubting that our British Coal-measures contain at 

 least one arborescent fern, equal in magnitude to those obtained 

 from the deposits at Autun. 



In his Memoir, Parts IX. and X., the author described, under 

 the provisional generic name of Zygosporites, some small 

 spherical bodies with furcate peripheral projections. Similar 

 bodies had been met with in France, and were regarded by 

 some of the French palceontologists as true Carboniferous repre- 

 sentatives of the Desmidiaceae. The author was unable to accept 

 this conclusion, deeming it much more probable that they would 

 prove to be spores of a different kind. Mr. Spencer exhibited 

 the specimen now described at the York meeting. It is a true 

 sporangium, containing a cluster of these Zygosporites. Though 

 they undoubtedly bear a close superficial resemblance to the 

 zygospores of the Desmidias, their inclosure within a common 

 sporangium demonstrates them to be something very different. 

 There is now no doubt but that they are the spores of the 

 strobilus, described by the author in his Memoir, Part V., 

 under the name of Volkmannia Dawsoni. Hence the genus 

 Zygosporites may be cancelled. 



Another interesting specimen found by Mr. Wild, is a young 

 Calamite, with a more curiously differentiated bark than any 

 that has hitherto been discovered. The structure of the vascular 

 cylinder and of the innermost layer of the bark, differs in no 

 essential respect from those previously described ; but the outer- 

 most portion displays an entirely new feature. It consists of a 

 narrow zone of 'Small longitudinal prosenchymatous bundles, 

 each one having a triangular transverse section, the apex of each 

 section being directed inwards, whilst their contiguous bases are 

 in contact with what appears to be a thin epidermal layer. As 

 in every previously discovered Calamite in which the cortex is 

 preserved, the peripheral surface of this specimen is perfectly 

 smooth or "entire." It displays no trace of the longitudinal 

 ridges and furrows seen in nearly all the traditional representa- 

 tions of Calamites figured in our text-books. 



It has long been seen that the medullary cells of the Lepido- 

 dendra, as well as the vessels of their non-exogenous medullary 

 sheaths, steadily increased in number as these two organs in- 

 creased in size correlatively with the corresponding general 

 growth of the plants. But the way in which that increase was 

 brought about has continued to be a mystery. The author now 

 describes a Lepidodendron "f the type of Z. Harcourlii in which 

 nearly every medullary cell is subdivided into two or more 

 younger cells, showing that, when originally entombed, the pith 

 was an extremely active form of meristem, though the branch 

 itself had attained to a diameter of at least two inches. The 

 numerous small young cells are of irregular form. Their deve 

 lopment by further growth into a regular parenchyma would 

 inevitably necessitate a corresponding increase in the diameter of 

 the branch as a whole ; and it must have been from these newly- 



formed cells that the medullary cylinder obtained the element 

 out of which to construct the additional vessels, the increase nf 

 which has been shown to be the invariable accompaniment of the 

 growth of the branch. As might be expected, the growth of the 

 vascular cylirder, or medullary sheath, could only have been a 

 centripetal one. 



A new form of Halonia from Arran is described. Instead of 

 its central piortion consisting, as in previously-described examples, 

 of the usual Lepidodendroid medulla surrounded by a vascular 

 cylinder, it consists of a solid axis of vessels, resembling in this 

 respect all the very young Lepidodendroid twigs previously 

 described from the same locality. Many recently obtained 

 specimens of Lepidodendroii branches sustain the author's 

 previous observations that all examples from Arran having less 

 than a certain diameter, have the solid axial bundle, wijilst all 

 above that diameter have a cylindrical vascular bundle inclosing 

 a cellular medulla. The first type commences with the smallest 

 twigs, and is found increasing gradually up to the diameter 

 referred to. The second type begins where the other ends, and 

 increases in diameter until attaining the dimensions of the largest 

 stems, in none of which does the solid bundle reappear. Halonial 

 branches have not hitherto been described attached to the 

 branches of any true Lepidodendron, though in 1871 (Memoir, 

 Part II.), the author gave reasons, based upon organisation, for 

 insisting that Halonia was a fruit-bearing branch of a Lepido- 

 dendroid tree. This conclusion was sustained by Mr. Carruthers 

 in 1873 in his description of a branch belonging to a Lepi- 

 dophloios. The author now figures a magnificent example, 

 from the museum of the Leeds Philosophical Society, of a 

 dichotomous branch of a true Lepidodendron of the type of Z. 

 elcgans and Z. s/laginoiclts. In this specimen every one of the 

 several terminal branches bears the characteristic Halonial 

 tubercles. The leaf scars of these latter branches have the 

 rhomboid firm, once deemed characteristic of the genus Bergeria, 

 whilst those of the lower part of the specimen are elongated as in 

 L. elegant, &c. These differences are not due to their appear- 

 ance in separate cortical layers of the branch, but to the more 

 rapid growth in length of its lower part compared with its 

 transverse growl b. 



The author throws some additional light upon the structure of 

 Sporocarpum ornatuin, described in Memoir, Part X., as also 

 upon the nature of the development of the double leaf-bundle-- 

 seen in transverse sections of the British Dadoxylons, described 

 in Memoir IX. After a prolonged but vain search for a structure 

 similar to the latter amongst the t« igs of the recent Conifers, the 

 author has at length found it in the young twigs of the Salisburia 

 adiantifolia . Sections of these twigs made immediately below 

 their terminal buds exhibit this germinal arrangement in the 

 most exact manner. Pairs of foliar bundles are given off from 

 the thin, exogenous Xylem zone which encloses the medulla, 

 whilst at the same points the continuity of the Xylem ring is 

 interrupted, as was al-o the case with the Dadoxylons, by an 

 extension of the medullary cells into the primitive cortex. Sec- 

 tions of the petiolar bases of the leaf -scales of the bud show that 

 these bundles enter each petiole in parallel pairs, subsequently 

 sub-dividing and ramifying in the Adiantiform leaf. This curious 

 resemblance between Salisburia and Dadoxylon, accompanied as 

 it is by other resemblances in the structure of the wood, bark, 

 and medulla, suggest the probability that our British Dadoxylon 

 was a Carboniferous plant of Salisburian type, of which Trigo- 

 nocarpum may well have been the fruit. If so, the further possi- 

 bility suggests itself that this plant may have been the ancestral 

 form whence sprang tbe Baieras of the Oolites, and, through 

 them, the true Salisburias of Cretaceous and of recent times. 



Linnean Society, May 4. — Sir J. Lubbock, Bait., F.R.S., 

 president, in the chair. — Dr. Cuthbert C. Gibbes was elected a 

 Fellow. — The Council and Fellows passed a resolution of sym- 

 pathy with the family of the late Mr. Chas. Danvin. — The Rev. 

 R. P. Murray called attention to specimens of Carex mon 

 tana obtained at Heathfield, Sussex, corroborating Mr. Roper's 

 late rediscovery of the plant in that county. — Mr. J. Murison 

 exhibited dried examples of Hclipterum eximium from tbe 

 Cape, of Ixodia achillcoides from South Australia, and of 

 jungle cotton from Nagpoor.- — A paper was read, on a col- 

 lection of algae from the Himalayas, described by Prof. O. 

 Dickie. — A communication was made, referring to new varieties 

 of the sugar-cane produced by planting in apposition, as asserted 

 by experiments of the Baron de Villa Franca and Dr. Glass of 

 Rio de Janeiro. In correspondence which had passed between 



