3. Sphærospyris globosa, n. sp. (Pl. [83], fig. 4).
Shell smooth, perfectly spherical, with small subregular circular pores. In the centre of the basal plate no larger collar pores. (The original collar pores are here of the same size as the other pores, and cannot therefore be distinguished.)
Dimensions.—Diameter of the shell 0.13, of the enclosed ring 0.06.
Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.
Genus 485. Nephrospyris,[[103]] Haeckel, 1881, Prodromus, p. 444.
Definition.—Androspyrida with a discoidal, kidney-shaped, or subcircular shell, with a basal incision; without transverse constriction and free basal feet.
The genus Nephrospyris is one of the most peculiar and most modified of the Spyroidea, of extraordinary size, in this respect surpassing all other genera of this suborder, and differing from them in its flat discoidal form. The diameter of the compressed shell often reaches one half millimetre or more; its perimeter is elliptical or nearly circular, smooth, constantly with a characteristic deep sternal incision or a basal sinus on the basal pole of the main axis. The central sagittal ring is comparatively small. The margin is often inflated like a delicate reticular girdle, and contains a large number of peculiar spherical or roundish nucleated cells (Pl. [90], figs. 6-10). According to the observations of Dr. John Murray, made on living Nephrospyris, they are Vorticellina, perhaps constant Symbiontes.
Subgenus 1. Nephrodictyum, Haeckel, 1881, Prodromus, p. 444.
Definition.—Network of the shell simple, with bars of nearly equal breadth.
1. Nephrospyris renilla, n. sp. (Pl. [90], figs. 9, 10).