REPORT ON THE RADIOLARIA. 1647 



Subfamily 1. LITHOGKOMIDA, Haeckel. 



Definition. C hallengerida without pharynx, with a simple mouth, not pro- 

 longed into an inner prominent tube. 



Genus 693. Lithogromia, 1 Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. 



Jena, Dec. 12, p. 5. 



Definition. C hallengerida without pharynx, without adoral teeth and marginal 

 spines. 



The genus Lithogromia and the two following genera represent together the sub- 

 family Lithogromida, comprising those Challengerida in which the mouth of the shell 

 is a simple opening, and not prolonged into a pharynx or an internal prominent tube. 

 Lithogromia may be regarded as the common ancestral form of this family, since it is 

 the simplest of all, and possesses no external apophyses, neither teeth on the mouth, nor 

 spines on the margin of the smooth shell. 



1. Lithogromia silicea, n. sp. (PI. 99, fig. 22). 



Shell ovate, one and a half times as long as broad, not compressed. Transverse section circular. 

 Mouth a simple circular opening with smooth edges about one-third as broad as the shell. 

 Dimensions. Length of the shell - 2, breadth 015; mouth 0'05. 

 Habitat. North Atlantic, Fserbe Channel (Gulf Stream), John Murray, depth 600 fathoms. 



2. Lithogromia diatomacea, n. sp. (PI. 99, fig. 21). 



Shell ovate, lenticular, one and one-third times as long as broad, strongly compressed. Trans- 

 verse section elliptical. Mouth a broad fissure, half as broad as the shell. 

 Dimensions. Length of the shell 0'27, breadth 0'2 ; mouth O'l. 

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



3. Lithogromia lenticula, n. sp. 



Shell subcircular, lenticular, about as long as broad, strongly compressed. Transverse section 

 lanceolate. Mouth a narrow fissure, one-third as broad as the shell 

 Dimensions. Diameter of the shell O'l 5, mouth 0'05. 

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



1 Lithogromia Siliceous Gromia. 



