1686 THE VOYAGE OF H.M.S. CHALLENGEE. 



8. Castanidium moseleyi, n. sp. (PI. 113, fig. 2). 



Pores -irregular, roundish or polygonal, two to four times as broad as the bars. Bristles about 

 as long as the diameter of one pore, or a little longer. Eadial main-spines cylindrical, irregularly 

 curved, somewhat longer than the diameter of the shell ; their base is more or less inflated and 

 fenestrated, therefore the shell is nearly polyhedral 



Dimensions. Diameter of the shell 0'7 to 0'8, of the pores O'Ol to 0'04. 



Habitat. Tropical Atlantic, Stations 346 to 349, surface. 



Genus 708. Castanissa, 1 Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. 



Jena, Dec. 12, p. 5. 



Definition. C as t an ell i da with simple radial main-spines and a dentate 

 mouth. 



The genus Castanissa agrees with the preceding Castanidium in the possession of 

 large radial main-spines, scattered between the numerous bristles or by-spines of the 

 surface ; but it differs from it in the possession of teeth around the mouth, identical 

 with those of Castanella ; it may be derived therefore either from the latter by 

 development of main-spines, or from the former by formation of teeth. 



1. Castanissa challengeri, n. sp. (PI. 113, fig. 1). 



Pores regular, circular, three times as broad as the bars. Bristles one-fourth as long as the 

 radius. Eadial main-spines (about twelve) very stout, straight, cylindrical, at the distal end 

 conical, pointed, with dimpled surface, about half as long as the radius. Mouth very large, circular, 

 about one-third as broad as the shell, with a corona of twelve to sixteen very large, triangular, 

 parallel teeth. 



Dimensions. Diameter of the shell 0'7 to 0'8, of the pores 0'03. 



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



2. Castanissa pearceyi, n. sp. 



Pores regular, circular, twice as broad as the bars. Bristles half as long as the radius. Eadial 

 main-spines (about twenty) slender, cylindrical, smooth, irregularly curved, about as long as the 

 radius. Mouth large, half as broad as the radius, with a corona of ten to twelve irregular, slender 

 teeth. 



Dimensions. Diameter of the shell 0'5 to 0'6, of the pores 0'02. 



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



1 Castanissa = Dimiuutive of Castanea. 



