1476 THE VOYAGE OF H.M.S. CHALLENGER. 



Dimensions.- Length of the shell (with five joints) 012 ; length of the fifth joint - 04, 

 breadth 0'08. 



Habitat. Central Pacific, Station 268, depth 2900 fathoms. 



Genus 643. Dictyomitra, 1 Zittel, 1876, Zeitschr. d. deutsch. geol. Gesellsch., p. 80. 



Definition. S tichocorida (vel Stichocyrtida eradiata aperta), with conical 

 shell gradually dilated towards the wide open month. Cephalis without horn. 



The genus Dictyomitra agrees with the preceding Lithostrobus in the slender, 

 conical form of the multiarticulate shell, but differs from it in the absence of a horn on 

 the cephalis ; the horn is here completely lost. 



Subgenus 1. Dictyomitrella, Haeckel. 

 Definition, Shell smooth, with joints nearly equal in length. 



1. Dictyomitra articulata, Haeckel. 



Eucyrtidium articulatum, Ehrenberg, 1875, Abhaudl. d. k. Akad. d. "VViss. Berlin, p. 70, 

 Taf. XL figs. 2, 3. 



Shell slender, conical, smooth, with six to eight deep strictures. All joints nearly equal in 

 length, gradually increasing in breadth, the eighth four times as broad as long, and twice as broad 

 as the fourth joint. In each joint three to four transverse series of small, regular, circular pores. 



Dimensions. Length of the shell (with eight joints) 0'12, of each joint O'OIS ; breadth of the 

 fourth joint 0'04, of the eighth joint '0'08. 



Habitat. Fossil in Barbados. 



2. Dictyomitra macilenta, Haeckel. 



Eucyrtidium macilentum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, 

 Taf. vii. fig. 15. 



Shell slender, conical, smooth, with five to seven deep strictures. All joints nearly equal in 

 length, gradually increasing in breadth, the sixth joint three times as broad as long, and twice as 

 broad as the second. In each joint only two transverse series of small, regular, circular pores. 



Dimensions. Length of the shell (with seven joints) 0'08, of each joint 0'012 ; breadth of the 

 sixth joint 0'036, of the second O'OIS. 



Habitat. Western Tropical Pacific, Stations 200 to 225, in various depths. 



1 Dictyomitra, Net-cap; S/XTBO*, 



