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Escharisphaeridia mantellii
Escharisphaeridia mantellii (Gitmez and Sarjeant, 1972) Courtinat, 1989
Originally Chytroeisphaeridia, subsequently Chytroeisphaeridia?, thirdly (and now) Escharisphaeridia.
Holotype: Gitmez and Sarjeant, 1972, pl.1, fig.3
Paratype: Gitmez and Sarjeant, 1972
Locus typicus: Kimmeridge Clay, H.M. Geological Survey Borehole, Warlingham, Surrey, England
Stratum typicum: Autissiodorensis Zone, Kimmeridgian
Translation Courtinat, 1989: LPP
Original diagnosis: Gitmez and Sarjeant, 1972, p.186: Chytroeisphaeridia mantelli
Shell subspherical to elongate. The periphragm is coarsely granular and bears an irregular scatter of tubercles and of low knobs, giving it a somewhat warty appearance. An apical archaeopyle is present, with slits extending posteriorly along presumed reflected sutures, producing a ragged appearance. The operculum most often remains attached to the ventral side of the shell.
Dimensions: Holotype: overall length 65 Ám, breadth 60 Ám. Paratype A: overall length (apex lacking) 60 Ám, breadth 65 Ám. Paratype B: overall length (apex lacking) 65 Ám, breadth 70 Ám. Range of Lower Kimmeridgian specimens: length (apex lacking) 25-75 Ám, breadth 30-65 Ám, measured specimens 12 in number. Range of Middle Kimmeridgian specimens: length (apex lacking) 40-80 Ám, breadth 50-75 Ám, measured specimens 16 in number. Range of Upper Kimmeridgian specimens: length (apex lacking) 23-70 Ám, breadth 28-75 Ám, measured specimens 12 in number.
According to these measurements, the species attained its largest size in the Middle Kimmeridgian.
Original description: Gitmez and Sarjeant, 1972, p.186-187: Chytroeisphaeridia mantelli
The thick shell wall is apparently composed of two layers: the inner layer thin, the outer layer making up almost the entire wall thickness. The ornamentation of the periphragm is of three types: coarse granules, small irregularly formed lumbs (verrucae) and rounded tubercles, irregularly scattered. A tabulation is indicated only by the slits; there is no suggestion of a cingulum. The sulcal notch was seen only in specimens in which the opcrculum was completely lost, it was not perceptible in specimcns with the operculum still attached. This is considered to indicate that when the operculum is present, it is attached to the ventral side of the cyst.
Courtinat, 1989, p.180:
Remark: The archaeopyle in Chytroeisphaeridia mantellii is apical which is not a characteristic of that genus. However, the operculum in this species is nit free, but adnate, attached to a sulcal(?) paraplate. Although the type species of the genus Escharisphaeridia (E. pococki) has a free operculum, E. mantellii is placed in this genus because the total of its characteristics other than the adnate operculum is that of Escharisphaeridia.
Originally Chytroeisphaeridia, subsequently Chytroeisphaeridia?, thirdly (and now) Escharisphaeridia.
Holotype: Gitmez and Sarjeant, 1972, pl.1, fig.3
Paratype: Gitmez and Sarjeant, 1972
Locus typicus: Kimmeridge Clay, H.M. Geological Survey Borehole, Warlingham, Surrey, England
Stratum typicum: Autissiodorensis Zone, Kimmeridgian
Translation Courtinat, 1989: LPP
Original diagnosis: Gitmez and Sarjeant, 1972, p.186: Chytroeisphaeridia mantelli
Shell subspherical to elongate. The periphragm is coarsely granular and bears an irregular scatter of tubercles and of low knobs, giving it a somewhat warty appearance. An apical archaeopyle is present, with slits extending posteriorly along presumed reflected sutures, producing a ragged appearance. The operculum most often remains attached to the ventral side of the shell.
Dimensions: Holotype: overall length 65 Ám, breadth 60 Ám. Paratype A: overall length (apex lacking) 60 Ám, breadth 65 Ám. Paratype B: overall length (apex lacking) 65 Ám, breadth 70 Ám. Range of Lower Kimmeridgian specimens: length (apex lacking) 25-75 Ám, breadth 30-65 Ám, measured specimens 12 in number. Range of Middle Kimmeridgian specimens: length (apex lacking) 40-80 Ám, breadth 50-75 Ám, measured specimens 16 in number. Range of Upper Kimmeridgian specimens: length (apex lacking) 23-70 Ám, breadth 28-75 Ám, measured specimens 12 in number.
According to these measurements, the species attained its largest size in the Middle Kimmeridgian.
Original description: Gitmez and Sarjeant, 1972, p.186-187: Chytroeisphaeridia mantelli
The thick shell wall is apparently composed of two layers: the inner layer thin, the outer layer making up almost the entire wall thickness. The ornamentation of the periphragm is of three types: coarse granules, small irregularly formed lumbs (verrucae) and rounded tubercles, irregularly scattered. A tabulation is indicated only by the slits; there is no suggestion of a cingulum. The sulcal notch was seen only in specimens in which the opcrculum was completely lost, it was not perceptible in specimcns with the operculum still attached. This is considered to indicate that when the operculum is present, it is attached to the ventral side of the cyst.
Courtinat, 1989, p.180:
Remark: The archaeopyle in Chytroeisphaeridia mantellii is apical which is not a characteristic of that genus. However, the operculum in this species is nit free, but adnate, attached to a sulcal(?) paraplate. Although the type species of the genus Escharisphaeridia (E. pococki) has a free operculum, E. mantellii is placed in this genus because the total of its characteristics other than the adnate operculum is that of Escharisphaeridia.