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Sethophormis pentalactis Haeckel, 1887

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Cephalis large, flat, hemispherical, with subregular, hexagonal pores. Thorax flat, campanulate, nearly hemispherical; also with subregular, hexagonal pores, and with five stout ribs. The three primary ribs of the thorax are complete, and reach the peristome; the two secondary ribs (as basal branches of the two lateral ribs) are incomplete and absent in the distal half of the thorax. Peristome denticulate, with an elegant marginal corona of small square pores and short conical spines.

Dimensions.—Cephalis 0.03 long, 0.06 broad; thorax 0.1 long, 0.2 broad.
Haeckel 1887
From Benson, 1966, p. 452-455; pl. 30, fig. 8 (not figs. 9-10):

Lampromitra cf. coronata Haeckel (partim.)

?Lampromitra coronata Haeckel, 1887, Challenger Rept., Zool. vol. 18, p. 1214, Pl. 60, fig. 7,7a.
?Sethophormis pentalactis Haeckel, 1887, Challenger Rept., Zool., vol. 18, p. 1244, Pl. 56, fig.5.

…dorsal and primary lateral bars free within thoracic cavity but eventually join thoracic wall, and extend as longitudinal thoracic ribs that terminate in relatively short, conical spines that extend beyond and below the mouth of the thorax; in a few tests the primary lateral bars are bifurcated where they join the thoracic wall, and each branch continues in the wall of the thorax as a rib.

From Remarks…. One specimen was observed with smaller thoracic pores that are nearly equal in size, thus not unlike Lampromitra coronata Haeckel (1887,. Pl. 60, figs. 7, 7a). The character of the dorsal and primary lateral bars and thoracic ribs of the Gulf species agrees well with L. coronata Haeckel. It differs from this species, however, in the lack of an apical horn twice as long as the cephalis, in generally larger polygonal thoracic pores, and in the presence of a single, not double, horizontal terminal flange. Without reference to Haeckel’s type material of this species positive identification is not possible.
Because the primary lateral thoracic ribs are bifurcated in a few specimens, they are similar to Sethophorrnis pentalactis Haeckel (1887, p. 1244, Pl. 56, fig.5). This species has a single, horizontal flange but smaller, more numerous, polygonal thoracic pores than those of the Gulf specimens.
Benson 1966


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