EEPOET ON THE KADIOLAEIA. 1101 



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 (PI. 90, figs. 6-10). Accord- 

 ing 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. (PI. 90, figs. 9, 10). 



Shell kidney-shaped, one and a half times as broad as long, and three tunes as long as the deep 

 kidney-shaped sternal incision. Ring with six pairs of branched apophyses, the bars of the 

 apical pair vertical, of the basal pair divergent. The corresponding bars of the two middle pairs 

 (on the frontal and the occipital face) form together on each side a large pentagonal or hexagonal 

 naso-orbital area, which is surrounded by four or five large polygonal meshes ; the other meshes 

 become smaller towards the inflated margin. All meshes simple, without arachnoidal framework. 



Dimensions. Shell 0'3 to 0'4 long, 0'4 to 0'5 broad ; ring 0'08 to 01 long. 



Habitat.-^- Central Pacific, Station 272, depth 2600 fathoms. 



2. Nephrospyris nephridium, n. sp. 



Shell kidney-shaped, one and two-third times as broad as long, very similar to the preceding species 

 (or only a variety of it ?). Ring with seven pairs of branched apophyses. The large naso-orbital 

 area is on the dorsal or occipital side simple, on the ventral or facial side divided by an equatorial 

 pair of transverse horizontal branches into two superior orbital, and two inferior nasal holes. 

 Sternal incision ovate. All meshes simple. 



Dimensions Shell 0'25 to 0'35 long, 04 to 0'5 broad ; ring 0'07 to 0'08 long. 



Habited. Central Pacific, Station 274, depth 2750 fathoms. 



3. Nephrospyris phaseolus, n. sp. 



Shell kidney-shaped, twice as broad as long, very similar to the two preceding species (or only 

 a variety of them ?). Ring with eight pairs of branched apophyses. The large naso-orbital area 

 (between the mitral and collar ring) is on the dorsal and on the ventral side divided by two 

 equatorial pairs of horizontal branches into two superior (orbital and occipital), and two inferior 

 (nasal and suboccipital) holes. Sternal incision cordate. All meshes simple. 



Dimensions. Shell 0'25 long, 0'5 broad ; ring 0'06 to 0'07 long. 



Habitat. Central Pacific, Station 266, depth 2750 fathoms. 



