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Spiniferites porosus
Spiniferites porosus (Manum and Cookson, 1964) Harland, 1973
Originally Hystrichosphaera, subsequently (and now) Spiniferites.
Holotype: Manum and Cookson 1964, pl.2, fig.2-3, text-fig.2
Locus typicus: Graham Island, Arctic Canada
Stratum typicum: Late Cretaceous
Original description: Manum and Cookson, 1964, p.11-12: Hystrichosphaera porosa
Shell circular to oval in outline, divided almost equally by a laevo-rotatory, girdle-like structure. Surface marked by distinct ridges into fields, five pre-equatorial, five post-equatorial, one antapical, and apparentlv one apical. A trapezium-shaped archeopyle with rounded upper limit is formed in the position of the median re-equatorial field. The "girdle" appears to be composed of five elongate fields. An irregularly outlined field suggestive of a longitudinal furrow is evident on the ventral surface between the ends of the "girdle". Shell-wall 1.0-1.5 µm thick, composed of two layers of which the outer one is a thin membrane less than 1/3 the total thickness of the wall. The ridges (c. 1 µm broad and high) marking the fields extend from the inner layer. The outer membrane forms flange-like extensions over the ridges and funnel-shaped appendages of approximately equal length but of somewhat varying width, situated more or less clearly at the angles of the fields. Rib-like branches which arise from the ridges pass into the appendages (usually one to each) and extend to their rims, usually bifurcating distally. The walls of the appendages are perforated to varying degrees. The perforations, which vary both in size and form, are particularly prominent in the distal expansions but usually present also in the stalks.
Dimensions: Holotype: shell diameter 66 x 75 µm, appendages 17-23 µm long. Range in shell diameter 66-98 µm, length of appendages 17-36 µm.
Supplemental description: Harland, 1973, p. 692
Proximo-chorate cyst, sphaeroidal to ovoidal in shape, made up of perphragm and endophragm closely appressed. The endophragm may be thickened; the periphragm makes up the processes. Cyst smooth. Tabulation present with the fields delimited by sutural ridges; no specimen, however, seen in which the tabulationcould be deciphered. Processes hollow, latispinous, erect, buccinate, open distally, fenestrate and digitate. One or two specimens observed in which the cilindrical sutural processes were present. Archaeopyle precingular of type P, formed by the loss of plate 3"".
Affinities:
Manum and Cookson, 1964, p.12: Hystrichosphaera porosa
H.porosa to some extent resembles H. tertiaria Eisenack & Gocht (1960 p. 515). The arrangement of the fields is similar, with the possible exception of the number at the apex and of those composing the "girdle", for which Eisenack & Gocht indicated three and four respectively as against our estimate of one and five for H. porosa. The general appearance of the appendages is also similar, but in H. tertiaria they appear, on the whole, to be somewhat more slender, and the perforations, which are such a prominent feature of H. porosa, are lacking.
Originally Hystrichosphaera, subsequently (and now) Spiniferites.
Holotype: Manum and Cookson 1964, pl.2, fig.2-3, text-fig.2
Locus typicus: Graham Island, Arctic Canada
Stratum typicum: Late Cretaceous
Original description: Manum and Cookson, 1964, p.11-12: Hystrichosphaera porosa
Shell circular to oval in outline, divided almost equally by a laevo-rotatory, girdle-like structure. Surface marked by distinct ridges into fields, five pre-equatorial, five post-equatorial, one antapical, and apparentlv one apical. A trapezium-shaped archeopyle with rounded upper limit is formed in the position of the median re-equatorial field. The "girdle" appears to be composed of five elongate fields. An irregularly outlined field suggestive of a longitudinal furrow is evident on the ventral surface between the ends of the "girdle". Shell-wall 1.0-1.5 µm thick, composed of two layers of which the outer one is a thin membrane less than 1/3 the total thickness of the wall. The ridges (c. 1 µm broad and high) marking the fields extend from the inner layer. The outer membrane forms flange-like extensions over the ridges and funnel-shaped appendages of approximately equal length but of somewhat varying width, situated more or less clearly at the angles of the fields. Rib-like branches which arise from the ridges pass into the appendages (usually one to each) and extend to their rims, usually bifurcating distally. The walls of the appendages are perforated to varying degrees. The perforations, which vary both in size and form, are particularly prominent in the distal expansions but usually present also in the stalks.
Dimensions: Holotype: shell diameter 66 x 75 µm, appendages 17-23 µm long. Range in shell diameter 66-98 µm, length of appendages 17-36 µm.
Supplemental description: Harland, 1973, p. 692
Proximo-chorate cyst, sphaeroidal to ovoidal in shape, made up of perphragm and endophragm closely appressed. The endophragm may be thickened; the periphragm makes up the processes. Cyst smooth. Tabulation present with the fields delimited by sutural ridges; no specimen, however, seen in which the tabulationcould be deciphered. Processes hollow, latispinous, erect, buccinate, open distally, fenestrate and digitate. One or two specimens observed in which the cilindrical sutural processes were present. Archaeopyle precingular of type P, formed by the loss of plate 3"".
Affinities:
Manum and Cookson, 1964, p.12: Hystrichosphaera porosa
H.porosa to some extent resembles H. tertiaria Eisenack & Gocht (1960 p. 515). The arrangement of the fields is similar, with the possible exception of the number at the apex and of those composing the "girdle", for which Eisenack & Gocht indicated three and four respectively as against our estimate of one and five for H. porosa. The general appearance of the appendages is also similar, but in H. tertiaria they appear, on the whole, to be somewhat more slender, and the perforations, which are such a prominent feature of H. porosa, are lacking.