A single anchor-thread, with its quadridentate terminal spathilla. [Illustration: COELOTHOLUS.] PLATE 123. LEGION PHÆODARIA. Order PHÆOCONCHIA. Family CONCHARIDA. (The central capsule is coloured red in the figures of this plate, the phæodium green). Fig. 1. _Concharium diatomeum_, n. sp., 1717 Dorsal view. The central capsule (red) exhibits above the anterior tubular main-opening (astropyle), and below the two small posterior lateral openings (right and left parapylæ). Fig. 2. _Concharium bivalvum_, n. sp., × 150 1717 Dorsal view. The central capsule is visible in the lower part, the margin of the two valves in the upper part of the figure. Fig. 2_a_ exhibits the two smooth lateral margins of the valves, catching into one another. (Lateral view). Fig. 3. _Concharium nucula_, n. sp., 1717 The dorsal valve alone, seen from the outside. Fig. 4. _Concharium bacillarium_, n. sp., 1718 Lateral view from the smooth margin, by which the two valves are united. Fig. 5. _Conchasma radiolites_, n. sp., × 300 1719 Lateral view. In the aboral half of the shell-cavity lies the red central capsule, in the oral half the green phæodium. Fig. 6. _Conchasma sphærulites_, n. sp., × 300 1719 Lateral view. On the aboral pole the two horns of the hinge. Fig. 7. _Conchellium tridacna_, n. sp., × 200 1720 Oblique lateral view (from the right and ventral side). Fig. 7_a_. Three pores of the same, with their hexagonal frames and six internal denticles, × 400 Fig. 8. _Conchopsis carinata_, n. sp., × 150 1725 Lateral view, from the left side. Fig. 9. Conchopsis lenticula, n. sp., × 150 1726 Lateral view, from the right side. The two membranes of the central capsule are separated by a wide interval in this and the preceding figure. The nucleus contains numerous nucleoli. Fig. 9_a_. Two of the peculiar cells, which are contained in the green phæodium in large numbers, × 400 [Illustration: 1.-4. CONCHARIUM, 5. 6. CONCHASMA, 7. CONCHELLIUM, 8. 9. CONCHOPSIS.] PLATE 124. LEGION PHÆODARIA. Order PHÆOCONCHIA. Family CONCHARIDA. Fig. 1. _Conchidium terebratula_, n. sp., × 400 1721 Lateral view, from the left side. Fig. 2. _Conchidium terebratula_, n. sp., × 800 1721 A piece of the frontal girdle-fissure, with the teeth of both valves catching into one another. Fig. 3. _Conchidium rhynchonella_, n. sp., × 200 1722 Lateral view, from the left side. Fig. 4. _Conchidium leptæna_, n. sp., × 300 1722