1688 THE VOYAGE OF H.M.S. CHALLENGER. 



confluent. The shell is very similar to the Astrosphseride Cladococcus (compare above 

 p. 223, PI. 27), but differs from it in the possession of the shell-mouth, absent in all 

 Sphseroidea. 



1. Castanopsis naresi, n. sp. (PI. 113, fig. 3). 



Pores subregular, circular, about twice as broad as the bars. Bristles twice as long as one 

 pore. Eadial main-spines somewhat shorter than the diameter of the shell, straight, cylindrical, in 

 the proximal half simple, in the distal half irregularly branched, each with ten to twelve partly 

 confluent branches. 



Dimensions. Diameter of the shell 06 to 0'7, of the pores 0'02 to 0'03. 



Habitat. Tropical Atlantic, Station 347 to 349, surface. 



2. Castanopsis macleari, n. sp. 



Pores irregular, roundish, two to four times as broad as bars. Bristles half as long as the 

 radius. Eadial main-spines about as long as the radius, stout and straight, cylindrical, forked 

 at the distal end, with two or three unequal fork-branches. 



Dimensions. Diameter of the shell 0'42, of the pores 0'015 to 0'03. 



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



3. Castanopsis fergusoni, n. sp. 



Pores irregular, roundish or polygonal, about as broad as the bars. Bristles three times as long 

 as one pore. Radial main-spines somewhat longer than the diameter of the shell, cylindrical, with 

 irregular and partly confluent lateral branches (similar to PI. 113, fig. 4a). 



Dimensions. Diameter of the shell 0'55, of the pores 0'012 to 0'016. 



Habitat. North Atlantic, Station 354, surface. 



Genus 710. Castanura, 1 Haeckel, 1879, Sitzuugsb. med.-nat. Gesellseh. Jena, 



Dec. 12, p. 5. 



Definition. C astanellida with branched radial main-spines and a dentate 

 mouth. 



The genus Castanura differs from the preceding Castanopsis in the possession of a 

 corona of teeth surrounding the mouth, similar to that of Castanissa. It differs from 

 the latter in the ramification of the radial main-spines, wherein it agrees with the 

 former. Castanura may therefore be derived either from Castanissa by ramification 

 of the main-spines, or from Castanopsis by development of teeth around the mouth. 



1 Castanwra = Chestnut with tails ; KOWTOWOH, oi>j. 



