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Concepts Giving an Idea of Mineral Paragenesis Under One Set of Given 428 SHORTER COMMUNICATIONS concepts giving an idea of mineral paragenesis under one set of given conditions, and that this concept cannot be generalised to bring in its fold rocks from widely separat­ ed areas and those of originally diverse chemical composition. Second, a resurvey on chemical lines of the qualitative petrographic data concerning metamorphism of calcareous rocks be made so as to evolve a working basis for investigations on such problems. REFERENCES RAMBERG, H., (1952) The origin 0/ Metamorphic and Metasomatic rocks, University of Chicago Press, 912 p. RINGWOOD, E., (1955) Principles of trace element distribution etc. Geochim. et, Cosmochim. et. Acta, v, 10, pp. 189-202; pp. 242-254. ON THE OCCURRENCE OF BURIADIA HETEROPHYLLA (FEISTM.) SEWARD AND SAHNI IN THE RANIGANJ STAGE (UPPER PERMIAN) OF INDIAN LOWER GONDWANA MANJU BANERJEE Botany Department, University of Calcutta, Calcutta Introduction: Buriadia Seward & Sahni, a dominant and characteristic plant fossil of the Karharbari Stage of Indian Lower Gondwana is rarely reported from the Barakar Stage (Ganguly, 1959) and its occurrence was not until now reported from the rich fossiliferous beds of the Raniganj Stage. Feistmantel (1881, p. 122, pI. 47A, figs. 20, 22, 24 and 19) described a few coniferous shoots and a cone scale from the Kamthi beds of Raniganj Stage as Voltzia heterophylla Brongn. Only one of these coniferous shoots (No. 5360, Feistm.; 1881 PI. 47A, fig. 22) and the cone scale (No. 5357, Feistm., 1881, PI. 47A, fig. 19) kept in the G.SJ. museum, Calcutta have been found on re-examination to be too poorly preserved for identification on the . basis of external morphology; the other specimens of Feistmantel having been mis­ placed were not available. Hence, the identification of the specimen as Voltzia heterophylla is doubtful and it is preferable to recognise it as coniferous shoot. Two species of Buriadia have been reported so far. B. heterophylla (Feistm.) Seward & Sahni has been recently investigated in detail by Pant & Nautiyal (1967). B. fragilis, the other species has been described by Maithy (1970). Material and method: The specimen preserved on a greyish sandy shale has a carbonised crust almost throughout the length of the preserved shoot. Macerated preparations with the carbonised crust have been made by HF and schulze solution followed by dilute KOH. , Specimen No.~PC. 274. Locality of collection-Pathargaria colliery, Bhurungia seam, Mahuda basin, Jharia coalfield. Bihar. Age and horizon-Raniganj Stage, Upper Permian. Description: External morphology-The unbranched foliage shoot measuring 6.5 cm.in length shows spirally arranged leaves which are attached to the stem by its entire base (Fig. I)... At.least two forms of leaves have been recognised; in general, 430 SHORTER COMMUNICATIONS in the wideness of the stomatiferous band in the third layer. The other ordinary cells of the stomatiferous band in both the layers are polygonal in shape and each of the cells show a papilla (Figs. 5-6). Stomata found in significant numbers are arranged irregularly. They are haplocheilic and monocyclic or incompletely amphi­ cyclic in nature. Subsidiary cells 5-7 in number are papillate and slightly smaller than the ordinary epidermal cells. The stomatal pore is longitudinal. Comparison and discussion: The external and internal morphology of the present specimen resemble closely those of B. heterophylla described in detail recently by Pant & Nautiyal (1967). The linear lanceolate leaves are occasionally forked; the cuticular layers of the bi-facial or tri-facial leaves show epidermal hairs, single non­ stomatiferous layer, and one or two stomatiferous layers with papillate epidermal cells flanking the stomatiferous strip. It is different from B.fragilis (Maithy, 1970) which has oblanceolate leaf with bluntly pointed apex and non-papillate cells flanking the stomatiferous strip. The present specimen is different from Walkmiella indica Surange & Singh (1953» and Paranocladus ? indica Surange & Lele (1956). W. indica has squamiform leaves and the epidermis of its bifacial leaves show 1-3 celled hairs, sinuous and toothed epidermal cells in the non-stomatiferous areas. In P. ? indica epidermal hairs are entirely absent. Buriadia resembling conifers in its external morphology, nature of wood, cuti­ cular structures etc. has been considered as unusual among the coniferales since it bears stalked 'Seeds singly on ordinary shoots among the leaves, and form no female cone; and accordingly it has been found to be uncIassifiable among the presently known gymnosperms. The systematic position of the genus is yet to be settled with the finding of definitely attached pollen bearing organs. Of the three genera ofconifers reported from Indian Lower Gondwana, W. indica and P. ? indica have been recorded from the Talchir and Barakar stages. Excepting the only report of the occurrence of poorly preserved coniferous shoots of dubious identification from the Kamthi beds (Feistmantel, 1881) conifers have not been recorded from the Raniganj Stage. The present report of the occurrence of B. heterophylla in the Raniganj Stage indicates that at least one genus of the conifers viz. Buriadia which flourished during the Karharbari Stage (Lower Permian), although fewer in number, is represented in the Glossopteris flora of the Raniganj Stage (Upper Permian). As such, the Biostratigraphic range-zone/Acrozone of Buriadia is limited up to Upper Permian. Acknowledgements: The author wishes to express her thanks to the Director­ General, Geological Survey of India, and to Mr. M. V. A. Sastry, Director and his colleagues in the Palaeontology Division, G.S.I., Calcutta for extending facilities for examining the museum specimens. Thanks are also due to Prof. A. K. Ghosh for his encouragement. RBFBRBNCES FB1STMANTEL, 0., (1881) The fossil flora of the Gondwana system. The flora of the Damuda­ - Panchet Divisions (conclusion). Mem. Geol. Sun Ind., Palaeont, indica, Ser. 12. v, 3, pt. 3, pp. 78-149. GANGULY, S., (1959) Palaeontological study of the Lower Gondwana rocks including the coak seams around Chirimiri of Surguja District, M.P. Quart. Journ. Geol. Min. Met. Soc. Ind., v. 31, p, ISS. SHORTER COMMUNICATIONS 431 "MAITHY, P. K., (1970) Studies in the Glossopteris flora of India·39. On some new plant fossils from the Karharbari beds, 'Giridih Coalfield, India. Palaeobotanist, v. 18, no. 2, pp. 167-172. ,PANT, D. D. and NAUTIYAL, D. D., (1967) On the structure of Buriadia heterophylla (Feistm.) Seward & Sahni and its fructification. Phil. Trans. Royl. Soc. London, Ser. B., no. 774, v. 252, pp. 27-48. ~SURANGE, K. R. and SINGH, P., (1953) The female dwarf shoot of Walkomiella indica-a coni­ fer from the Lower Gondwanas of India. Palaeobotanist, v. 2, pp. 5-8. -- and LELE, K. M., (1956) Plant fossils from the Talchir beds of the South Rewa Gond­ wana basin. Palaeobotanist, v. 5, no. 2, pp. 82-91. ON THE OCCURRENCE OF CARBONATITES IN THE VINAYAKAPURAM-KUNAVARAM NEPHELINE SYENITE BAND, KHAMMAM DISTRICT, ANDHRA PRADESH Y. JANARDAN RAO AND I. S. N. MURTHY Department of Geology, Osmania University, Hyderabad The occurrence of two small patches of carbonatites in the Vinayakapuram­ Kunavaram nepheline syenite band reported by Sharma et al. (1971) brings to light certain interesting problems on the origin of this complex and in particular on the problems of carbonatite. The authors have earlier recorded these occurrences (Janardan Rao and Murthy, 1970, p. 58) in the southern part of the complex and their presence elsewhere is of interest. The carbonatite veins, as stated above, are mostly found in the southern parts of. the area, south of Mamilurgudem (17°22'50' : 81°6'). They occur along fracture planes in nepheline syenites trending along NE-SW, NW-SE and also along the cross joints of the band. They are found in the form of thin veins with width ranging from 1 em to 5 em, and length from a few metres to 30 metres. At places, mutual cross -cutting relationships of these veins are noted. In contrast to the general whitish grey nepheline syenite outcrops of this region, the outcrops of hastingsite-nepheline­ -syenites where the carbonatite veins are noted are of pale pink buff colour wherein nepheline is altered to a product of red brick colour, and felspar, instead of the usual white, is now of pale pink colour. The contact between the two rock types is sharp (Fig. I). Further, within the carbonatite vein itself there is sharp demarcation between the medium grained and fine grained layers-the latter being, in general, towards the contacts. The carbonatite is greyish green in colour, constituting a fine grained calcite mass in which clots of calcite crystals are embedded. Fine biotite flakes, felspar and nepheline are randomly distributed and more conspicuously noticed in the medium grained layers. Under the microscope, the carbonatite shows porphyritic texture in which the large crystals are of calcite, K-felspar, hastingsite, biotite, alkali amphibole, apatite, nepheline, and zircon are embedded in a groundmass of felspar (Fig. 2). The felspar megacrysts appear to be actually clusters of smaller aggregates. Calcite is the predominant mineral and is randomly distributed showing corroded or diffuse borders. At places, it is found that the groundmass material not only encroaches.
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