3. Rhopalocanium cortinium, n. sp.
Shell slender, ovate, nearly of the same form as, and with similar fenestration to that of Theopera cortina, (Pl. [67], fig. 8). It differs from the latter mainly by the absence of the three thoracic ribs, characteristic of Theopera. Length of the three joints = 1 : 2 : 6, breadth = 1 : 4 : 4. The three wings arise by a broad, triangular, striated base from the upper half of the abdomen, below the lumbar stricture. The cephalic horn and the three divergent wings are shorter, and at the distal end not so much thickened as in Theopera cortina.
Dimensions.—Length of the three joints, a 0.025, b 0.045, c 0.12; breadth, a 0.03, b 0.07, c 0.08.
Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.
4. Rhopalocanium pythia, n. sp.
Rhopalocanium ornatum, Bury, 1862, Polycystins of Barbados, pl. vi. fig. 1.
Shell nearly ovate, with two deep strictures. Length of the three joints = 1 : 4 : 8, breadth = 1 : 4 : 4. Cephalis subspherical, with a conical horn of three times the length. Thorax inflated, abdomen inversely campanulate and prolonged into a short, conical, latticed tube. Pores subregular, circular. Three wings slender, as long as the abdomen, arising by a broader base from the uppermost part of the abdomen, their thickened end being curved inwards.
Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.15; breadth, a 0.03, b 0.08, c 0.07.
Habitat.—Fossil in Barbados.
5. Rhopalocanium delphicum, n. sp. (Pl. [67], fig. 9).