Genus 619. Theocorys,[[236]] Haeckel, 1881, Prodromus, p. 434.
Definition.—Theocorida (vel Tricyrtida eradiata aperta) with ovate abdomen, broader than the constricted mouth. Cephalis with a single horn.
The genus Theocorys and the two following closely allied genera, united formerly with Eucyrtidium, differ from the preceding Theocorida in the constriction of the peristome, so that the inflated abdomen is broader than the terminal mouth. They represent, therefore, the transition to the Theocapsida, with closed mouth. The abdomen is commonly more or less ovate or barrel-shaped, sometimes inversely conical. The cephalis of Theocorys bears a single apical horn.
Subgenus 1. Theocoronium, Haeckel.
Definition.—Pores of the thorax and of the abdomen of nearly equal size and similar form.
1. Theocorys turgidula, Haeckel.
Eucyrtidium turgidulum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 13.
Shell slender, ovate, with two deep strictures, very fragile and thin-walled. Length of the three joints = 2 : 5 : 7, breadth = 2 : 6 : 6. Cephalis subspherical, with a pyramidal horn of the same length. Thorax nearly spherical. Abdomen ovate, twice as broad as the constricted mouth. Pores very numerous, regular hexagonal, three to four times as broad as the bars.
Dimensions.—Length of the three joints, a 0.015, b 0.05, c 0.07; breadth, a 0.02, b 0.06, c 0.06.
Habitat.—Tropical Pacific (Philippine Sea), Stations 206 and 224, surface.