1662 THE VOYAGE OF H.M.S. CHALLENGER. 



1. Pharyngella monoceros, n. sp. 



Shell ovate, slightly compressed, with a single large tooth on the dorsal corner of the peristome. 

 The tooth is cylindro-eonical, half as long as the shell, straight or slightly curved, and lies in the 

 main axis of the shell. Pharynx cylindrical, straight, half as long as the shell-radius. This species 

 is very similar to ChaUengeria tritonis (PL 99, fig. 5), and to the common cosmopolitan Challengeria 

 naresii, but differs generically from them in the possession of the pharynx. 



Dimensions. Diameter of the shell 0'25 to - 28 ; length of the tooth 014. 



Habitat. Tropical Atlantic, Station 348, depth 2450 fathoms. 



2. Pharyngella gastrula, n. sp. (PI. 99, fig. 18). 



Shell ovate. Peristome with two parallel, vertical, straight, pointed teeth, which are half as 

 long as the shell-radius. Pharynx of the same length, cylindrical or funnel-shaped, its outer 

 aperture scarcely broader than the inner. 



Dimensions. Length of the shell 0'3 to 36, breadth 0'24 to 03; teeth and pharynx 0'07 to 0'09. 



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



3. Pharyngella invaginata, n. sp. 



Shell circular, slightly compressed or nearly spherical. Peristome with two parallel, vertical, 

 straight, pointed teeth, which are about as long as the shell-radius. Pharynx of the same length, 

 funnel-shaped ; its outer aperture twice as broad as the inner. 



Dimensions. Diameter of the shell 0'2 to 0'22, teeth and pharynx 0'05. 



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



4. Pharyngella gastrcea, n. sp. (PI. 99, fig. 17). 



Shell broad, ovate or nearly circular, lenticular, strongly compressed. Peristome with two 

 parallel, pointed teeth, which are nearly as long as the shell-radius, slightly curved, and obliquely 

 inclined over the mouth. Pharynx half as long, cylindrical, obliquely descending ; its outer and 

 inner apertures of equal breadth. 



Dimensions. Diameter of the shell 0'3 to 0'33, teeth 0'12, pharynx 0'06. 



Habitat. South Atlantic, Stations 328 to 334, surface. 



Genus 698. Porcupinia, 1 Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. 



Jena, Dec. 12, p. 5. 



Definition. C hallengerida with a pharynx, with teeth on the mouth and 

 marginal spines. 



The genus Porcupinia differs from the preceding Pharyngella in the development 



1 Porcupinia, in memory of H.M.S. " Porcupine" by which the first British deep-sea explorations were carried out 

 during the years 1869 and 1870. 



