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Theocorythium vetulum Nigrini, 1971

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Shell quite smooth and usually thin-walled. Cephalis trilocular, the paired lobes beneath and only slightly lateral to the larger unpaired lobe; pores small, subcircular. Stout, three-bladed, apical horn, between equal to and twice the cephalic length. Primary lateral and dorsal spines continue as ribs in the thoracic wall for about half its length, but have not been observed to project externally.
Thorax cupola-shaped with circular to subcircular pores arranged longitudinally, 7-10 in a vertical series, 12-15 on a half-equator. Pronounced lumbra stricture.
Abdomen inflated conical. Pores similar in size, shape and arrangement to those of thorax, 5-12 in a vertical series, 12-17 on a half-equator. Distally, a row of three-bladed subterminal teeth is usually present. Sligth terminal constriction to termination at a poreless peristome and up to eleven triangular terminal teeth which may or may not be well-developed. Figured specimens from SDSE 62, 1028-30vm, USNM No. 650937.
Deimensions (based on 20 specimens): Total length (excluding apical horn and terminal teeth) 137-182µ. Length of cephalis 27-36µ; of thorax 45-63µ; of abdomen (excluding terminal teeth) 45-90µ. Maximum breadth of cephalis 27-36µ; of thorax 81-90; of abdomen 90-128µ.
Nigrini 1971











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