1660 THE VOYAGE OF H.M.S. CHALLENGER. 



divergent teeth ; the terminal teeth are the halves of a forked dorsal tooth and diverge laterally ; 

 the lower teeth are nearly horizontal and directed ventrally. 



Dimensions. Diameter of the shell 013 to 015 ; length of the peristome - 07 to 01. 



Habitat. Tropical Pacific, Stations 274 to 276, depth 2350 to 2750 fathoms. 



25. Challengeron wyvillei, n. sp. (PL 99, fig. 15). 



Shell ovate, lenticular, strongly compressed, with numerous (forty to fifty) short, conical, radial 

 spines on the margin ; the spines are larger on the ahoral side and spinulate. Peristome narrow, 

 with two parallel, lateral, lamellar, forked teeth, about as long as the radius ; the upper branch 

 of the forks is sabre-shaped, obliquely truncate, subvertical, ciliate, and much broader than the 

 lower nearly horizontal branch, which is directed towards the ventral side and curved upwards. 



Dimensions. Length of the shell 012 to 016, breadth 01 to 014 ; length of the peristome 

 0-08 to Oil. 



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



Subfamily 2. PHARYNGELLIDA, Haeckel. 



Definition. Ch allengerida with a pharynx, or an internal prominent mouth 

 tube. 



Genus 696. Entocannula, 1 Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. 



Jena, Dec. 12, p. 5. 



Definition. C hallengerida with a pharynx, without teeth on the mouth, and 

 without marginal spines. 



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

 family Pharyngellida, differing from the preceding Lithogromida in the development of 

 a peculiar pharynx, an internal, cylindrical, or funnel-shaped tube, which is conspicuous, 

 leads from the mouth into the shell-cavity, and is provided with an inner and an outer 

 opening. The Pharyngellida are much rarer than the Lithogromida ; only ten species have 

 been observed of the former, fifty of the latter. Entocannula is the simplest form of 

 the Pharyngellida, having a smooth shell, without aboral teeth and marginal spines ; it 

 differs from Lithogromia only in the possession of the pharynx. One remarkable 

 species is covered entirely with extremely thin, flinty hairs, and may represent therefore 

 a peculiar genus, Trichogromia. 



1 Entoeannula Shell with an internal tube. 



