G8 THE VOYAGE OF H.M.S. CHALLENGER. 



Dimensions. Diameter of the shell 0'12, pores O'Ol to 0'03, bars 0'004. 

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



33. Cenosphcera aspera, Stohr. 



Cenosphaera aspera, Stohr, 1880, Palseontogr. Bd. xxvi. p. 85, Taf. i. fig. 2. 



Shell thick walled, rough, covered with short conical papillae. Pores irregular, roundish, of about 

 the same breadth as the bars, eight to twelve on the quadrant. 



Dimensions. Diameter of the shell O'l7, pores and bars O'Ol to 0'04. 

 Habitat. Fossil in Tertiary rocks of Sicily ; Grotte, Stohr. 



34. Cenosphcera hirsuta, Ehrenberg. 



Cenosphcera hirsuta, Ehrenberg, 1872, AbhandL d. k. Akad. d. Wiss., Berlin, p. 287, Taf. x. fig. 18. 



Shell thin walled, rough, covered with innumerable very short bristles. Pores very irregular, 

 roundish, of about the same breadth as the bars. 



Dimensions. Diameter of the shell O'll, pores and bars 0'002 to 0'012. 

 Habitat. Indian Ocean, Zanzibar, Pullen ; depth 2200 fathoms. 



Genus 16. Stigmosphcera, 1 Haeckel, n. gen. 



Definition. L iosphserida with one single latticed sphere, with simple shell- 

 pores (not prolonged into free tubuli) ; in the central point of the spherical shell-cavity 

 are united a number of radial beams, which become forked and inserted into the inner 

 surface of the -shell by their distal ends. 



The genus Stigmosphcera differs from Cenosphcera (and from all other Monosphse- 

 rida) by internal radial beams, which are united in the centre of the simple spherical shell ; 

 these beams are branched, and the distal ends of the branches inserted on the internal 

 surface of the shell. I have observed only two, nearly identical specimens of this genus, 

 both with regular, hexagonal pores and thin bars ; the beams were implanted in the 

 corners of the hexagons. In one specimen the surface was covered with short radial bristles, 

 whilst these in the other specimen were prolonged into radial spines (like AcanthosplifKra]. 

 Possibly this peculiar genus is derived from Carposphcera, by reduction and loss of 

 a central medullary shell. 



Stigmosphcera actinocentra, n. sp. 



Shell very thin walled, rough, with regular circular, hexagonally framed pores, six times as 



broad as the bars, eight to ten on the quadrant ; in the corner of each hexagon a small bristle. In 



1 Stigmosphcera = Sphere with central point ; miyfta, 



