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Microdinium veligerum
Microdinium veligerum (Deflandre, 1937) Davey, 1969; Emendations: Lejeune-Carpentier, 1943, p.B24–B25, as Ceratocorys veligera; Lejeune-Carpentier and Sarjeant, 1983, p.5–6, as Rhiptocorys veligera.
NOW Rhiptocorys. Originally Micrhystridium, subsequently Ceratocorys, thirdly Microdinium, fourthly Microdinium?, fifthly (and now) Rhiptocorys, sixthly Phanerodinium, seventhly Phanerodinium?.
Tax. sr. synonym of Microdinium irregulare Clarke and Verdier, 1967, according to Below, 1987.
Tax. sr. synonym of Microdinium smolenskiense (Vozzhennikova, 1967) Lentin and Williams, 1973, according to Below, 1987. Lentin and Vozzhennikova, 1990, retained Microdinium (as Rhiptocorys) smolenskiense as a separate species.
Stover and Evitt, 1978, considered this to be a problematical species of Microdinium.
Holotype: Deflandre, 1937, pl.12 [al. pl.9], fig.9
Locus typicus:
Stratum typicum: Senonian
Supplemental description: Davey, 1969, p.136
The shell is ovoidal, densely granular and bears a number of high crests delimiting a tabulation. The crests are distinctive, beillg 1 to 5 Ám in height, with typically a smooth outer margin. They consist of tuo memblanes, joined distally and diverging proximally to form a broad base, 1 to 3 Ám, wide to the crest. There is between the two membranes a crestal cavity which is occasionally subdivided by septa, particularly where two crests diverge. Here a conical chamber is usually found. The reflected tabulation appears to be 1", ?5", 6c, 6""", 1p, 1"""". The hypotract is considerably larger than the epitract, the latter being devoid of crests and usually possessing a pentagonal apical archaeopyle. The shape of the latter is the only indication that there are five precingular plates. The cingulum is broad and does not appear to be spiral. Plate 1""", and to a lesser extent 2""", are reduced to accommodate the posterior intercalary plate. The remaining four postcingular plates are large and there is a single large antapical plate. The sulcus is very narrow just posterior to the cingulum and then widens rapidly towards the antapex. The sulcus extends onto the epitract where it sometimes bears five small sulcal plates.
Range of observed specimens: shell length 28 (31.5) 38 Ám, width 25 (28.2) 32 Ám.
NOW Rhiptocorys. Originally Micrhystridium, subsequently Ceratocorys, thirdly Microdinium, fourthly Microdinium?, fifthly (and now) Rhiptocorys, sixthly Phanerodinium, seventhly Phanerodinium?.
Tax. sr. synonym of Microdinium irregulare Clarke and Verdier, 1967, according to Below, 1987.
Tax. sr. synonym of Microdinium smolenskiense (Vozzhennikova, 1967) Lentin and Williams, 1973, according to Below, 1987. Lentin and Vozzhennikova, 1990, retained Microdinium (as Rhiptocorys) smolenskiense as a separate species.
Stover and Evitt, 1978, considered this to be a problematical species of Microdinium.
Holotype: Deflandre, 1937, pl.12 [al. pl.9], fig.9
Locus typicus:
Stratum typicum: Senonian
Supplemental description: Davey, 1969, p.136
The shell is ovoidal, densely granular and bears a number of high crests delimiting a tabulation. The crests are distinctive, beillg 1 to 5 Ám in height, with typically a smooth outer margin. They consist of tuo memblanes, joined distally and diverging proximally to form a broad base, 1 to 3 Ám, wide to the crest. There is between the two membranes a crestal cavity which is occasionally subdivided by septa, particularly where two crests diverge. Here a conical chamber is usually found. The reflected tabulation appears to be 1", ?5", 6c, 6""", 1p, 1"""". The hypotract is considerably larger than the epitract, the latter being devoid of crests and usually possessing a pentagonal apical archaeopyle. The shape of the latter is the only indication that there are five precingular plates. The cingulum is broad and does not appear to be spiral. Plate 1""", and to a lesser extent 2""", are reduced to accommodate the posterior intercalary plate. The remaining four postcingular plates are large and there is a single large antapical plate. The sulcus is very narrow just posterior to the cingulum and then widens rapidly towards the antapex. The sulcus extends onto the epitract where it sometimes bears five small sulcal plates.
Range of observed specimens: shell length 28 (31.5) 38 Ám, width 25 (28.2) 32 Ám.