Back
Omatidium amphiacanthum
Omatidium amphiacanthum (Cookson and Eisenack, 1958) Courtinat in Courtinat and Gaillard, 1980
Originally Hystrichodinium, subsequently Hystrichodinium?, thirdly (and now) Omatidium.
Holotype: Cookson and Eisenack, 1958, pl.5, fig.9
Locus typicus: Omati, Papua
Stratum typicum: Late Jurassic or Neocomian
Original description: Cookson and Eisenack, 1958, p. 37: Hystrichodinium amphiacanthum
This is a delicate form and most of the specimens are imperfectly preserved. The shell of the type is almost sphaerical and is provided with a narrow, faintly marked girdle and nine processes, four at one pole, five at the other. The processes are long and pointed, and widen towards the membrane. The membrane of the shell is delicate and no trace of surface markings remains. The main features of this species, i.e., the median girdle and the polar position of the processes, have been confimed by less perfect paratypes.
Dimensions: Type - 173 µm overall, shell 52 x 71 µm; processes 43-62 µm long.
Poulsen 1996, p. 85
Omatidium amphiacanthum (Cookson & Eisenack 1958) Courtinat 1980, Pl. 21, Fig. 7
Remarks. This Australian species have been recorded in France by Courtinat and Gaillard (1980) and Courtinat (1989). The Australian forms have longer spines, but Courtinat (in Courtinat and Gaillard (1980) referred the European form to the Australian species without question. This interpretation is followed here.
Recorded occurrence. Poland: Hypselocyclum Zone.
Originally Hystrichodinium, subsequently Hystrichodinium?, thirdly (and now) Omatidium.
Holotype: Cookson and Eisenack, 1958, pl.5, fig.9
Locus typicus: Omati, Papua
Stratum typicum: Late Jurassic or Neocomian
Original description: Cookson and Eisenack, 1958, p. 37: Hystrichodinium amphiacanthum
This is a delicate form and most of the specimens are imperfectly preserved. The shell of the type is almost sphaerical and is provided with a narrow, faintly marked girdle and nine processes, four at one pole, five at the other. The processes are long and pointed, and widen towards the membrane. The membrane of the shell is delicate and no trace of surface markings remains. The main features of this species, i.e., the median girdle and the polar position of the processes, have been confimed by less perfect paratypes.
Dimensions: Type - 173 µm overall, shell 52 x 71 µm; processes 43-62 µm long.
Poulsen 1996, p. 85
Omatidium amphiacanthum (Cookson & Eisenack 1958) Courtinat 1980, Pl. 21, Fig. 7
Remarks. This Australian species have been recorded in France by Courtinat and Gaillard (1980) and Courtinat (1989). The Australian forms have longer spines, but Courtinat (in Courtinat and Gaillard (1980) referred the European form to the Australian species without question. This interpretation is followed here.
Recorded occurrence. Poland: Hypselocyclum Zone.