1200 THE VOYAGE OF H.M.S. CHALLENGER. 



17. .Dictyophimus triserratus, n. sp. (PI. 61, fig. 17). 



Shell three-sided pyramidal, with slight collar stricture. Eelative length of the two joints = 

 1 : 3, breadth = 1:4. Cephalis small, subspherical, with a large pyramidal horn three times as long. 

 Thorax with much larger, irregular roundish, double-edged pores, and three prominent, serrate ribs, 

 which are prolonged into three pyramidal strongly divergent feet of the same length. 



Dimensions. Cephalis 0'02 long, 0'02 broad; thorax 0'06 long, O09 broad. 



Habitat. Central Pacific, Station 274, depth 2750 fathoms. 



18. Dictyophimus bicornis, n. sp. 



Shell thorny, with deep collar stricture. Eelative length of the two joints = 2:3, breadth = 2:3. 

 Cephalis nearly as large as the thorax, subglobular, with numerous small, circular pores, and two 

 divergent pyramidal horns of half the length (a major occipital and a minor frontal horn). Thorax 

 three-sided pyramidal, with larger irregular pores and three serrate ribs, which are prolonged into 

 three prismatic spiny feet of half the length. (Differs from the similar Dictyophimus sphccrocephalus, 

 PI, 57, fig. 10, mainly in the double horn and the spinulate feet.) 



Dimensions. Cephalis 0'05 long, 0'05 broad ; thorax 0'08 long, 0'07 broad. 



Habitat. Western Tropical Pacific, Station 225, depth 4475 fathoms. 



19. Dictyophimus pocillum, Ehrenbcrg. 



Dictyophimus pocillum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. v. 

 fig. 6. 



Shell thorny, with distinct collar stricture. Relative length of the two joints =1:5, breadth = 1:5. 

 Cephalis nearly spherical, with numerous small conical spines. Thorax flat, three-sided pyramidal 

 with large, irregular, roundish pores, and three strong, widely divergent, spinulate ribs, which are 

 prolonged into three prismatic spinulate feet of the same length. 



Dimensions. Cephalis 0'03 long, 0'03 broad ; thorax 015 long, 015 broad. 



Habitat. Fossil in Barbados. 



20. Dictyophimus cienkowskii, n. sp. (PI. 60, fig. 1). 



Lamprotripus sijuarrosus, Haeckel, 1881, Prodromus et Atlas. 



Shell spiny, flatly pyramidal, with slight collar stricture. Relative length of the two joints = 1:3, 

 breadth =2:6. Cephalis flat, cap-shaped, three times as long as broad, with numerous bristle- 

 shaped spines three times as long. Thorax also spiny, with irregular, very large, polygonal meshes 

 and thin bars ; its three ribs prolonged into three very long and thin, widely divergent, prismatic 

 feet, bearing numerous long spines on the three edges. 



Dimensions. Cephalis 0'025 long, 0'05 broad; thorax 0'075 long, 015 broad. 



Habitat. North Pacific, Station 250, surface. 



