Volume 75, Issue 1
January 1972, pages 1-54
pp 1-14 January 1972
A total of thirty-three species and two varieties of pelagic tunicates are reported from the western part of the Bay of Bengal. The influence of the prevailing water movements, temperature and salinity on the distribution of pelagic tunicates at the surface and in the subsurface is considered. The suitability ofOikopleura intermedia, Fritillaria borealis f. sargassi, Fritillaria pellucida, Thalia democratica var.orientalis and the western-Pacific form ofThalia democratica as indicators of water movements is suggested.
pp 15-22 January 1972
An account is given of the yard and field trials conducted at Cuttack which showed that ‘Gramoxone’ (20% paraquat) at 0·1 to 0·2 kg/ha. (a.i.) gave complete control ofPistia stratiotes in one to two weeks’ time. The cost of clearance by the weedicide worked out to Rs. 64–93/ha as against Rs. 168–178/ha. for manual clearance. Treatment in instalments is recommended to avoid oxygen depletion due to rotting of treated weed mass and consequent fish mortality.
pp 23-31 January 1972
The ebb and flow of the tides in an estuary affect not only the hydrographical conditions but also to a marked extent the abundance of zooplankton populations. Observations were made during one particular cycle studied during February 1961. Water samples and plankton were collected at regular intervals of two hours at a fixed station in the mid-estuarine region of the river Godavari. The temperature of the waters seems to follow the course of the day and the atmospheric conditions, rather than the tides, whereas the salinity variations during 24-hour period closely followed the tides. The incoming tides contribute to an increase in the salinity of the estuarine waters. The volume of plankton collected appears to have some relationship with the nature of the tide, strength of the current and the direction of the flow of water. The distribution and abundance of different groups of zooplankton in the estuary were found not only to follow the tides, but more so the diurnal rhythm. The abundance of zooplankton during night was many times higher than during the day and particularly copepods and veligers showed greater densities during the night.
pp 32-39 January 1972
The rhizome ofDennstaedtia appendiculata var.elwesii andD. scabra is creeping, slender, sparsely branched and covered by multicellular, uniseriate, acicular, gland-tipped, non-chlorophyllous hairs. The ground tissue is parenchymatous. The vascular cylinder is siphonostelic, pierced by two alternate, closely placed, dorsal rows of small non-overlapping leaf gaps. Leaf trace is solitary, broad, gutter-shaped and placed lateral to the leaf gap. Branching is dichotomous and the branch trace is siphonostelic; there are no branch gaps. The leaf is 2–3-pinnate with the stipe and rachis cylindrical and adaxially grooved; the adaxial groove of the branches of the rachises are interrupted at the base. Vascular connection to the secondary rachis is extramarginal. The ultimate segments of the leaf are small and bear multicellular, uniseriate hairs on both the surfaces. The sori are terminal on the apices of the veinlets (mostly on the apex of the superior basal veinlet so that only one sorus per segment is present), and protected by cup-shaped indusia which are glabrous. The sporangial stalk is 3–4 cells long and 3 cells thick at the apex. The spores are trilete with the exine smooth or bearing small circular protuberances. Spore germination is of the Vittaria-type and prothallial development of the Adiantum-type. Adult prothallus is cordatethalloid bearing leptosporangiate-type of sex organs. MorphologicallyDennstaedtia is very close toMicrolepia.
pp 40-50 January 1972
A few terrestrial strips of the Coringa river banks were examined to understand the floristic patterns and some of the associated edaphic factors. The present study shows the existence of distinct vegetational zones under the prevailing influence of salinity.
pp 51-54 January 1972