志摩木場洪積統の有孔蟲類

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Of the 80 species of Foraminifera listed above, notes on new species and some indeterminable forms are given in the Japanese lines, while the new genera would be interesting to micro-palaeontologists of all countries., Geminospira n., gen., Type: Geminospira simaensis n., sp., Test obscurely rotaliform, turreted, unequally compressed laterally ; chambers incompletely biserial, inner chambers smaller and less in number than outer chambers ; distal wall inflated, with a groove on the ventral side ; aperture narrow, on inner border near suture ; wall calcareous, finely perforate., Geminospira simaensis n., sp., Test elongate oval, dorso-ventrally compressed, dorsal side flatly convex, ventral side more convex, periphery rounded ; early chambers of microspheric form compactly coiled as in Rotalia, later uncoiled forming arcuate adult part, chambers in two rows, 8 to 11 outer chambers and 6 to 8 inner chambers, inner chambers smaller, lunate in cross section, a little embracing dorsal inflation of outer chamber ; a few early inner chambers invisible from ventral side ; sutures not much depressed, carly outer sutures feebly limbate, early inner sutures slightly apressed ; distal wall inflate, furnished with a groove on its ventral slope and just in front of the median suture extending in spiral direction ; apertural slit on the inside border of the last outer chamber along the suture with the last inner chamber, not extending below the groove., Holotype : length, 0.,52 mm., width, 0.,24 mm., A paratype : length, 0.,45 mm., thickness, 0.,14 mm., This species is apparently in relation with Bulimina convoluta WILLIAMSON, 1858 which seem to be another species of Geminospira, Geminospira convoluta from Torres Strait figured by BRADY shows oblique outer sutures and a zigzag median suture unlike the present new species., Moreover it differs from the latter in having more strongly coiled test and much wider inner chambers., In some specimens of Geminospira simaensis, the inner chambers are elongate and oblique to the median suture., It is not certain that this genus is allied with Buliminidae, but it seems to have something common with Cancris and Baggina., Oolitella n., gen., Type : Oolitella irregularis n., sp., Test irregular, chambers usualy inflated, variable in form and size, without regular arrangement, first chamber tubular ; wall thin, very finely perforate ; aperture circular with an internal tube, free at the inner end., Oolitella irregularis n., sp., Test very variable without a definite form ; chambers up to 7, irregularly ovoid, not in spiral or linear arrangement, addition of a new chamber taking place upon any part of the earlier chamber ; suture sometimes constricted ; first chamber tubular, smaller than the rest ; wall thin very finely perforate ; aperture entosolenian ; maximum long axis of chamber, 0.,35 mm., This very special form the Pleistocene of Sima is quite new to our knowledge., It is like Adherentina SPANDEL, 1909 and Cayeuxina GALLOWAY, 1933 in outline, but it is clear that they are not in relation., The young examples have some common characters with Entosolenia WILLIAMSON, 1858, such as in substance, fine perforation, aperture and interior tube., Monothalamous Entosolenia is said to be a later form of the complex phyletic lines of Buliminidae., Oolitella may be a form a step later thaN Entosolenia, in which the early way of chamber arraogement has been missed.,
日本地質学会の論文
1941-05-20

著者

槇山次郎
東京帝国大学理学部地質学科

志摩木場洪積統の有孔蟲類

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