1100 THE VOYAGE OF H.M.S. CHALLENGEE. 



The genus Splmrospyris differs from all other S p y r o i d e a in the regular spherical 

 or spheroidal form of the lattice-shell. It may therefore be easily confounded with some 

 species of the Sphaeroidea; but the internal sagittal ring, placed in the median plane 

 of the fenestrated sphere and connected with it by radial beams, leaves no doubt that it 

 is derived from a true Spyroid, either Dictyospyris or Amphisjjyris, or another genus. 

 Sometimes also four larger collar pores are visible. 



1. Sphcerospyris sphcera, Haeckel. 



Dictyospyris sphcera, BiitscUi, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. pp. 511, 539, 

 Taf. xxxii. fig. 15, a, h. 



Shell smooth, nearly spherical, slightly flattened at the base, with small regular circular pores. 

 In the centre of the basal plate a regular rectangular cross with four equal collar pores. 

 Dimensions. — Diameter of the shell Oil, of the enclosed ring 0'06. 

 Habitat. — Fossil in Barbados. 



2. Sphcerospyo'is quadriforis, n. sp. 



Shell rough, nearly spherical, shghtly flattened at the base, with small regular circular pores. 

 In the centre of the basal plate a bilateral symmetrical cross with four ovate collar pores ; two 

 cardinal pores twice as large as the two jugular pores and six to eight times as broad as the other 

 shell-pores. 



Dimensions. — Diameter of the shell 0-26, of the enclosed ring 0'09. 



Habitat. — South Atlantic, Station 332, depth 2200 fathoms. 



3. Sphcerospyris globosa, n. sp. (PI. 83, fig. 4). 



SheU smooth, perfectly spherical, with smaU 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 013, of the enclosed ring 0'06. 



Habitat. — Tropical Atlantic, Station 347, depth 2250 fathoms. 



Genus 485. Nephrospyris,^ Haeckel, 1881, Prodromus, p. 444. 



Definition — A ndrospyrida 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 aU other genera of this 



1 Nephrospyris = Kidney-shaped basket ; mpjoV, avv^is. 



