STRATIGRAPHY 'AND PALYNOLOGY OF THE MANGROVE SWAMPS OF BOMBAY

VISHNU -MITTRE Birbal'Sahni Institute' of Palaeobotany, Lucknow-226007 & STATIRA GUZDER Deccan College, Poona

" ABSTRACT sand or shingle are exposed at different The mangrove swamps in Bombay and Salsette places along the shores. The soils in these islaIld-s are made up up to 5 m of dark and brown islands are derived from basalt and rocks m,up..filling undulating .rocky basins. Pollen ana• of felsic and ultrabasic composition asso• lysis .h,as revaled statistical insufficiency of pollen ciated with trap and from the intertrappeans gra~ris, the' identification o.f which perJ,Ilits us to infer"btoadly"an' increase of Rhizophorae (Bru• made up of yellow, green or black often guiera and Ceriops).in the top samples; Avicennia laminated or stratified pyroclastic shelly was poorly present and there are indications of the material. presence of the other important mangrove genera The climate is of the monsoon type, with among which pollen grains of .Sonneratia acida outnumber those of others. The sediments have a rainless and comparatively cool period been found to abound in microplankton and micro• from November to February; a hot dry forms, and the latter have indeed escaped the season from March to May and a very wet d,estructive effects of the acetolysis method. The season during June to September. The lack of organic matter and poverty of pollen have not permitted the building up of radiocarbon dated aver~ge annual precipitation is 220 cm pollen stratigraphy for these mangr6ve swamps. with a maximum of 350 cm and a minimum The possibilities for the prevalence of relatively of 156 cm. moister climate in the past have been discussed. The upland forest, the best example of which occurs in the neighbourhood of the INTRODUCTION is the Deciduous' Monsoon Forest, described by Champion and Seth (1968) as the Southern Tropical Moist of India between Lats. IS055'N and OMBAY, situated on the west coast Deciduous Forest. Remains of the original B-19°20'N, Longs. 72°45'E and 73°0'E, forest also occur on the eastern slopes of is made up of seven islands now welded Hill and on the chain of hills into one. Separated from the mainland, between the Agra Road and the Vehar and it covers an area of 169 square miles, lying Tulsi lakes. No tree in the undisturb'ed along a north-south axis extending from forest is more than the 15% of the total. Ghodbunder in the north to Point Common trees in these forests include in the south, and its northern limit in the Acacia chundra Willd., Syzygium cumini Salsette Islands is much broader than the Skeels, Erythrina indica Lamk., Butea mono• tapering south. sperma Taub., Bauhinia racemosa Lamk., The Ulhas River flowing into the Bassein Ficus spp., Manilkara hexandra Dub., Lannea Creek and the Thana Creek separate the coromendalina Merr., Terminalia crenulata islands of Bombay and Salsette from the Roth., Pongamia pinnata Pier., Morinda mainland, and 'the Mahim Creek separates tinctoria HD.f., Wright£a tinctoria RBr., them from each other. The coastal margin Salmalia malabarica and species of Trema, along the west is indented by smaller creeks, Adina, Grewia, Bridelia, Mitragyna, Ster• while the Harbour waters surround Bombay culia, Garuga, Gmelina, Dalbergia and Mangi• on the east. Extensive tidal flats separate fera indica. Among the less common species the island: of Trombay' from Bombay and are of Schleichera, Diospyros, Hymendictyon, the Salsette Islands, the latter being the Gardenia, Casearia, Anogeissus, Randia, etc. largest of all the islands. Most of the tree species are insect-pollinated The sea bordering the islands of Bombay and of the others the pollen grains lack and Salsette is shallow, and rocks, mud, distinguishing criteria - the pollen being 111 112 THE PALAEO BOTANIST

3-colpate or 3-colporate with more or less the bunds beyond the reach of the sea smooth walls. The climbers and the shrubs water. in the forest are also largely insect-polli• Both the mangrove and the upland nated. vegetation have been intensely affected by The mangrove vegetation in the tidal biotic factor, to provide fuel and fodder marshes consists of Avicennia alba which is and land for cultivation, for roads, for the chief and dominant component together housing estates. Several badly disfigured wi th A vicennia ojJicinalis, A canthus ilici• trees are a witness to this. More specifi• jolius, Ceriops candolleana, Aegiceras majus, cally the branches of Butea trees are cut off Bruguiera gymnorhiza, species of Sonneratia and burnt to provide ash on the rice fields; and Rhizophora, Salicornia brachiata, Clero• Alangium and Manilkara are cut to make dendrum inerme, Lumnitzera racemosa and walking sticks; Sterculia urens is damaged Excoecaria agallocha. by incisions to obtain gum. During the course of field work in 1962 Human interference with the mangrove by one of us (Vishnu-Mittre), and in 1969 vegetation to collect fuel and provide by both of us Avicennia alba was found to fodder for cattle, the browsing of buffaloes be the dominant element occurring e~ther and bulls on the foliage and flowers of pure or mixed with Acanthus and other Avicennia spp. and Acanthus ilicijolius species. Both Rhizophora and Bruguiera (Navalkar, 1956) have resulted in the stunt• occur only rarely. The succession of plant ed and bushy forms of these species, which communities from the coast moving inland are rarely allowed to attain a height above studied and described by Navalkar (1956) 2 m. These biotic factors have also contri• and modified by us, is given below: buted substantially to the selective decline a) Rhizophora mucronata community is of certain species, the relative increase of nearest the sea, abutting on mud and sand others and have arrested vegetational suc• along the edge of the creek at Ghodbunder cession at the Avicennia alba stage, if not and also on the edge of the Bassein Creek. deflected it. The upland forests have be• Even in these two areas there is now consi• come bare of undergrowth, and elsewhere derable reduction in the number of Rhizo• their ruthless destruction has induced such phora trees. light-demanders and waste land species as b) Avicennia alba community. Behind Bambusa arundinacea and Lantana to invade the Rhizophora community, an almost pure the cleared areas. Certain trees which were community of Avicennia alba is seen in spared during clearance have increased, many places (Colaba, from Sewri to Trom• thus changing the vegetational pattern. bay, Vadalla, south of , Madh The tidal marshes being waterlogged Island, etc.), with occasional small bushes and badly aerated are suitable situations of A. ojJicinalisand a few clumps of Acanthus for pollen analytical investigation in order ilicijolius. At other places, such as at to build the history of the mangrove vege• Mahim, Ceriops candolleana, Bruguiera gym• tation and of the upland forests and to norhiza and Sonneratia apetala also occur, infer therefrom a sequence of climatic though rarely, in the Avicennia community. changes. The pollen analytical work was, c) Acanthus ilicijolius zone fringing the therefore, undertaken of some of these Avicennia Community. marshes so as to expand our knowledge of d) Aeluropus villosus zone outside the the environmental background of early man Acanthus zone. This is either a pure dis• in the Bombay region and to assess correctly tinguishable zone or more often it is also the role of environmental changes in shaping populated by Suaeda jruticosa, Sesuvium the various human cultures of which archaeo• portulacastrum and Clerodendrum inerme. logical evidence has been found. The individual colonies of these species are Briefly, the archaeological succession in found intermixed in the zone. this area covers the Early, Middle and e) Approaching dry soil, Clerodendrum Late Stone Ages. The Middle and Late inernie forms a conspicuous belt together Stone Age tools have been found by with grasses (species of Sporobolus, Panicum Tod (1939), Malik (1959), Sankalia (1962) paspalum) and sedges such as Cyperus and by one of uS (Statira Guzder). These compressus and C. rotundus and species of are observed both in the nala sections at Fimbristylis. Clerodendrum also grows on Borivili and Kandivili and on the surface VISHNU-MITTRE & GUZDER-STRATIGRAPHY AND PALYNOLOGY OF MANGROVES 113

of the coastal headlands at Erangal, Manori + I + I 111 I I 1 1 1+ 1 I 1 1 and Gorai. If the strata in which the M.S.A. tools are found can be correlated with or found to terminate at the base of + 1 I I I I I I I I 1 1 1 1 1 1 I the raised beach deposits, it will be possible to place these tools in a known chronological horizon. The discovery of a submerged forest at ++ I I I I I I I I 1 1 1 1 1 1 1 Prince's Dock, Bombay (La Touche, 1919) and the occurrence of raised beaches along the coast are suggestive of sea level ++ 11 I I 1 I I I 1 1 1 1 1 1 1 changes. It is also intended to date these events and to determine whether they resulted from eustasy, isostasy or tectonic movements and to relate these events to +++ I 1+1 I I I 1 1 1 I 1 1 I stages of forest evolution, climatic change and human cultures.

+1+11+111111+1+1+ STRATIGRAPHY

+ III + II I I 1 I I 1 I I I I Bore holes have been dug at various places with the help of a Hiller-type sampler. It must be admitted that beyond a particular depth (generally 4 metres) it was impossible, +++++ 1+ I I ++ I I I I 1+ even with extra force, to push the borer deeper. In 1962 borings were made by the senior + I + I ++ I I 1 I I I I I + I I author accompanied by his assistants, at Kurla, Ghodbunder, Thana Creek, Meet Bu,nder, Mahim Creek and Madh-Marve. + I + I I + I + I I I I + I ++ I The sediments were found to consist of a silty mud of dark? or blue colour with occasional woody fragments (roots and + II I I I I 1 III I I I I I I rootlets of modern vegetation). The sedi• ments were of a homogenous nature through• out, except for the overlying 30-90 cm of brown mud. + I I I 1+1 I I I I I + I + I I At Kurla, the bed rock was encountered at a depth of 130 cm; the top 75 cm were of brown mud and the rest dark ? mud. +++ I ++ I I I + I I +++ I I The section at Ghodbunder extended to a depth of oVer 5 m. The details of the boreholes at Kurla and Ghodbunder are + I I I 1 I I I I I I I I I I I I shown below:

Kurla Ghodbunder em em

Brown mud 0-75 Brown mud 0-90 ..• Dark mud 75-130 Dark mud 90-150 Rock Blue mud 150-510

At the other sites the brown mud varied in thickness from 25 to 80 em and the rest of the profile consisted only of blue mud. 114 THE PALAEOBOTANlST

The depth of the profiles varied between unpublished annual pollen calendar cons• 3 and 4 m. In the marginal sections only tructed by Miss Olive Anchen at the K.E.M. and not towards the centre of the swamps it Hospital, Bombay which shows an over-all was possible to strike the bed rock. No poverty of pollen on the slides. Pollen horizon of organic deposit such as peat or grains of neither the mangrove species nor a submerged forest was encountered. The those of the deciduous forest are present borings revealed that the floor of the basin in the aerial pollen content. This could was undulating. be due to dominance of insect-pollinated In 1969 we conducted borings in the species in the forest or to low pollen pro• marshes at (Bandholi) 72°46'5" duction or else the circulation of wind E, 19°19'N and at Bassein (Naigaon) 72° currents being unfavourable for the dis• 48'E 19°19'N. The overlying brown mud semination of pollen within the city. The of varying thickness was noted here too, pollen content of modern surface and water below it the blue mud varies between 3 to 5 samples in relation to the composition of cm and overlies a dark, grey impenetrable forest remains to be worked out. For the plastic clay. Its thickness remains undeter• relative amount of pollen grains produced mined. Shell fragments and fabricated by mangrove plants we have largely depend• plant tissue, sometimes carbonized, have ed upon the observations of Muller (1964). been detected at varying depths. Rhizophora, Ceriops, and Bruguiera are high pollen producers. Sonneratia spp. with large and showy flowers also produce large POLLEN ANALYSES amounts of pollen grains, while Avicennia, the most common mangrove plant, produces Samples for pollen analysis were collected little pollen. Among the other members, at intervals of 5 cm throughout the profile, Acanthus ilicijolius, Clerodendrum inerme but from Manori and Aksa they were and Sesuvium are insect-pollinated. The spaced at 10 cm and 2·5 cm intervals. The members of Chenopodiaceae are high pollen samples were treated with 10% KOH, producers. then HF, subsequently acetolysed and This distribution of species of Mangrove finally mounted in glycerine. The coarse plants (Table 1) in the Bombay marshes debris left on the sieve after alkali treatment reveals that Rhizophora is founC! at three was examined under a low-power binocular sites: Ghodbunder, Bassein and along the microscope. No seeds or fruits were found. Kamdevi River, but more profusely at But for a few indeterminate fragments or Ghodbunder than at the other two sites. shreds of cuticles and several microforamini• Sonneratia occurs more profusely at Ghod• fera, nothing else was found.' Organic bunder than at Mahim. Bruguiera and material derived from plants was extremely Ceriops occur sporadically both at Ghod• poor*. bunder and Mahim. Thus, the large pollen To support the identification of sub fossil producers are extremely rare in Bombay pollen and spores, pollen slides of modern today. Sonneratia is abundant on the mangrove plant species prepared by the eastern side of the Elephanta Island, and acetolysis method were examined and their extends over a much wider area than morphological details drawn up in the form that covered by Avicennia. Rhizophora of a workable key to assist identification. has recently been discovered there (F. R. The key was enlarged by incorporating Bharucha, personal communication). morphological details of the pollen of all the marine, estuarine and fresh water plants of India. A similar broadly based RESULTS pollen key was prepared of some wind• pollinated species of the deciduous forests of The lack of sufficient pollen in the Bombay Bombay. marshes was discovered by one of us (Vishnu• . The only information available on the Mittre) in 1962-63. Detailed analyses now modern pollen content at Bombay is the carried out have confirmed these obser• vations. The total number of pollen grains *That is why the samples collected for C14 recovered in each sample even after attempts assay did not yield sufficient carbon for dating. to concentrate the pollen content was under VtSHNU-MITTRE & GUZDER - STRATIGRAPHY AND PALYNOLOGY OF MANGROVES l1S

100 and in many samples it was less than ~icroforar.ninifera 50 - quite insufficient for any statistical A comparatively large number of micro• evaluation. In view of our inability to foraminifera have been observed on the construct a pollen diagram, only the following slides, despite HCI and HF treatment. co~ments base~ on small numbers of pollen graIns are possIble. They are abundant in the upper part of the profile. A slight decrease is noted at 1·5 m. . 1. Pollen grains of Rhizophorae, increase In the top samples. Pollen of Rhizophora They are absent below 3 m. Their size mucronata has not been recovered. Pro• ranges from 25 p. to 160 p.. Biserial and the close-coiled forms are the dominant bably.Bruguiera and Ceriops are the species represented. ones; next in the order of abundance are the Globigerina- type and the loose-coiled forms. . 2. .(1vicennia type pollen is poorly present In spIte of the dominance of A. alba. The Uniserial types and Ostracods are poorly 3. Mangrove vegetation also consisted of represented. Ex.coecaria agallocha, Carallia sp., Sonneratia It is J.IDusualfor Foraminifera to escape aczda and Acanthus ilicijolius, as indicated destructIon by the acetolysis method• but their presence in these slides and their by small numbers of their pollen grains. small size, are factors, similar to those At?0ng these the pollen grains of Sonneratia recorded elsewhere by Wilson and Hoff• aczda are comparatively more numerous than those of the others. meister (1952), Wetzel (1957), van Veen 4. Pollen of Chenopodiaceae suggests the (1957), Muller (1959). The present con• former occurrence of Suaeda maritima and census of opinion would indicate that these Atriplex spp. are the .chitinous inner linings of the tests 5. Pollen of marine angiosperms has not of ma~Ine foraminif~rCl;' Their relatively been found. small SIze, however, dIstInguishes them from 6. Pollen grains of the upland vegetation more common genera, hence the term suggests the former presence of Malvaceae microforaminifera, referring to "these small (Salmalia malabarica), Myrtaceae, Legumi• but sometimes fully grown representatives of a restricted gr~lUpof genera" (Muller 1959). nosae, Euphorbiaceae (Phyllanthus), Holop• Dr S. N. SIngh and Dr P. Kalia of the te~ea, MelJaceae and Urticaceae, together ~lth groun~ vegetation comprising Compo• G.eology Dept., Lucknow University very sitae, CrucIferae and Gramineae. Their kmdly processed, without any acid treat• pollen grains are, however, extremely poorly ment, a part of a sample given to them present. and identified the following species of 7. Large-sized grass pollen (82-100 p.) foramini~era in it: B.olivina sp., Bulimina sp., encountered at a depth of 140-145 cm in Text~lana, 4~~oma sp., Rotalia sp., Dis• the profile from Madh Island is interesting. corbt.s sp., Ctbtctdes sp., Elphidium corispum, -It could be of Maize (Zea mays L.), Flortlus scaphum, Hastigerina, Orbulina uni• 'now held to have been introduced into versa and Spiroloculina indica. Il!~ia in pre-Columbian times. The possi., They. are of i.nterest in this study from the :pomt. o~ vI.ew that their presence is ,bIltty cannot 1?e overlooked that it might certamly IndIcatIve of salt-water conditions !hav~ been den.ved from a wild grass pro• ducmg large-sIzed pollen (Vishnu-Mittre and their re.lat~ve in~rease/decrease may be 1973). ' found to COInCIdeWith the rise/fall of sea level. We are indeed incompetent to under• ! 8. Amo~g the fresh-water species, a single pollen gram of Typha has been found in a take study of microforms in this regard. bottom sample. 9. A few pollen grains of Abies/Picea ~icroplankton have been found in the lowermost sample in the Madh profile at a depth of 3'90-4'00 m. As many as seven types of microplankton T~ese two. genera today occur in the were observed of which Types I and V are Hl~alayas and their pollen in Bombay is dominant in the lower samples and Types ObVIOusly due to long-distance transport. II and III are dominant in top samples. !l0we.ver, sil!ce they are encountered only In the absence of any detailed studies they In a SIngleslIde, the possibility of laboratory have been tentatively indentified d. Paleao• contamination cannot be overruled. hystrichosphora and d. Baltisphaeridium. 116 THE PALAEOBOTANIST

CONCLUSION in marine sediments. Koreneva's observa• tions on the palynology of bottom sediments The lack of sufficient pollen grains in the from the Pacific Ocean (Koreneva, 1964) marshes of Bombay has vitiated the object are indeed revealing in this respect. She of building a pollen sequence from them. finds the greatest concentration of pollen We can hardly draw any conclusion from grains in argillaceous silts, high concentra• the small numbers of pollen grains recovered, tions in depression sediments of sub-marine since the indications of species can not be relief and in coastal regions where coarsely properly assessed in relation to low and aleuritic and arenaceous fractions occur. high pollen production. Avicennia pollen But there is a sharp drop in the pollen-spore is inadequately present in spite of Avicennia content in sediments of amorphous silica being the dominant community in the which reflects rapid accumulation of diatoms. region. This may perhaps be due to its The proportion of fine sand and silt in the low pollen production and the biotic influence mangrove soil of Bombay varies from 68% - removal of young flowering shoots for to 71·3% while the coarse sand 'is only fodder. Pollen of Rhizophora has not been 3-5% (Navalkar, 1941). identified, indicating its extremely poor Alkalinity of the soil may be responsible occurrence in the past as at present. High for the destruction of pollen. The soils of values of other Rhizophorae perhaps sug• the Bombay mangrove swamps are more or gests that they were more profusely present less neutral with pH 6·81 in cold season in the past. Sonneratia acida was also and pH 7·03 during the Monsoon. The sea more abundant in the past than it is today. water however is distinctly alkaline with pH The presence of Excoecaria agallocha, Carallia more than 8 (Navalkar & Bharucha, 1948). sp., and Acanthus ilicijolius is also recorded. Surprisingly it has been discovered that Both Suaeda spp. and Atriplex also occurred. the mangrove soils in spite of their water• Indications of the upland forest have logged condition and poor aeration - suit• also been obtained. Pollen of Gramineae able environment for the deposition of could have been derived from the grasses organic matter, are very deficient in humus. on the drier areas surrounding the man• The humus content varies between 1 and groves or from the forest. If large sized 2% in the Bombay mangrove soils (Navalkar pollen at a depth of 140-145 cm is really & Bharucha, 1949). It is believed by that of maize this level can not be consi• Navalkar and Bharucha that the decaying dered older than 1500 A.D. (Vishnu-Mittre organic matter is probably washed out by the & Gupta, 1966). tides, hence the low humus content. If this Pollen of Typha is decidedly from the is true then this could be one of the factors fresh water swamps in the vicinity but the responsible for lack of sufficient pollen in these conifer pollen appears to have been derived sedimerlts. Their (Navalkar & Bharucha, from the Himalaya, almost from an areal op. cit.) observations are substantiated by distance of over 1500 km. our findings of lack of sufficient organic The paucity of pollen and spores in these matter in samples collected for C-14 assay. sediments may be due to low pollen pro• If the inference of increased occurrence duction of these species, to the destruction of Sonneratia, Bruguiera and Ceriops in the of pollen in these sedimen.ts or to the high past from the meagre pollen record be rate of sedimentation in these swamps. considered reliable then it may indicate The soils of the modern marshes of Bombay different environmental conditions in the bearing mangrove vegetation are charac• past. The chloride content of the cell sap terized by a chloride content (0·78 to 3.47) of these species has been found to be much almost as high as in sea water (0'91-3'59) lower (2'52-2'81) than that of Avicennia (Bharucha & Navalkar, 1942), thou~h rai-?-• alba (3'11-4'40). The present dominance fall and temperature cause fluctuatIOns 1ll of Avicennia is held to be due to the higher this concen.tration. We are as yet ignorant chloride content of its cell sap than of the of whether a high concentration of chloride sea water, consequently the other species in the soils has a destructi ve effect on with a lower content are not able to thrive. pollen grains in general and on those of The chloride content of sea water is 3·17• mangrove plants in particular. Nevertheless 3·59 during the cold and 3-43-3·50 in the pollen of terrestrial plants has been recorded hot seasons and it ranges between 0·91 and VtSHNU-MITTRE & GUZDER-STRATtGRAPHY Mm PALYNOLOGY OF MANGROVES 117

2'83 during the rainy season. For the at the Tata Institute of Fundamental frequent occurrence of the species Rhizo• Research, Bombay for all the help towards phora, Ceriops and Sonneratia the decreased field work and for facilities in the laboratory chloride content during the monsoon should of the Geophysics Group at TIFR. To be most suitable and this would require a Professor F. R. Bharucha and Dr. B. S. higher and more equally distributed pre• Navalkar formerly of Institute of Science, cipitation throughout the year. From this Bombay, our thanks are due for helpful it appears that the former abundance of discussions on the ecology and phytogeo• these species in Bombay where today they graphy of the mangrove swamps of Bombay. are extremely rare was due to the prevalence We are highly indebted to Professor P. V. of moister climatic conditions. Bole of St. Xavier's College, Bombay for the identification of plants and provision of polleniferous materials of the mangrove ACKNOWLEDGEMENT plant species. We are also grateful to Dr. S. N. Singh and Dr. P. Kalia of the Geology We have the pleasure to record our Dept. of Lucknow University for examining thanks to Professor D. Lal and his colleagues microforams in one of the samples.

REFERENCES

BHARUCHA,F. R. (1969). Personal communication. NAVALKAR, B. S. & BHARucHA, F. R. (1948). BHARucHA, F. R. & NAVALKAR, B. S. (1942). Studies in the Ecology of Mangroves IV. The Studies in the Ecology of Mangroves III. pH Concentration of the Sea-water, Soil Solu• The Chloride content of Seawater, Soil Solution tion and the Leaf Cell-Sap of the Mangroves and the Leaf Cell-sap of the Mangroves. J. Univ. Bombay. 14 (5); 35-45. Jour. Univ. Bombay. 10 (5): 97-106. Idem (1949). Studies in the Ecology of Mangroves. CHAMPION,H. G. & SETH, S. K. (1968). A Revised V. Chemical Factors of the Mangrove Soil. Survey of the Forest Types in India. Delhi. Ibid. 18 (3): 17-35. KORENEVA, E. V. (1964). Distribution of Spores SANKALIA,H. D. (1962). Stone Age Cultures of and Pollen of Terrestrial Plants in Bottom Bombay, A Reappraisal. J. Asiatic. Soc. Sediments of the Pacific ocean. Ancient Bombay. (N.S.), 34-35; 120-131. Pacific Floras. University of Hawaii Press: 31. TOD, K. R. U. (1939). Palaeolithic Industries of LA TOUCHE, 1'. H. D. (1919). The Submerged Bombay. J. R. Anth. Inst., 69 (2): 257-272. Forest at Bombay. Rec. geol. Surv. India. 49 VEEN, F. R. VAN (1957). Microforaminifera. (4): 214-218. Micropalaeontology. 3 (1); 74. MALIK, S. C. (1959). Stone Age Industries of the VISHNU-MITTRE (1973). Cereal vS. non-cereal Bombay and Satara Districts. M.S. Univ. grass pollen and the inference of past agri• Archaeology Series, 4, Baroda. culture. In "Pollen and Spore Morphology MULLER, J. (1959). Palynology of Recent Orinoco of the Recent Plants. Proc. III Internat. delta and shelf sediment: Reports of the Orinoco Palynological ConI Novosibirsk, U.S.S.R. 1971: Shelf Expedition. Micropalaeontology. 5 (1): 24-32. 1-32. VISHNU-MITTRE & GUPTA, H. P. (1966). Pollen Idem (1964). A Palynological Contribution to morphological studies of some primitive varieties the History of the Mangrove Vegetation in of Maize (Zea Mays L.) with remarks on the Borneo. Ancient Pacific Floras. University of history of maize in India. Palaeobotanist. 15 Hawaii Press: 33-42. (1-2): 176-184. NAVALKAR,B. S. (1941). Studies in the Ecology WETZEL, O. (1957). Fossil " Microforaminifera •• of Mangroves II. Physical Factors of the in various sediments and their reaction to acid Mangrove Soil. J. Univ. Bombay. 9 (5): 78-91. treatment. Micropalaeontology. 3 (1): 61-64. Idem (1956). Geographical Distribution of the WILSON, L. R. & HOFFMEISTER, W. S. (1952). Halophytic Plants of Bombay and Salsette Small Foraminifera. Micropalaeontologist. 6 (2); Islands. J. Bombay. Nat. Hist. Soc. 53 (3): 1-11. 26-28.