Dimensions.—Length of the shell (with six joints) 0.16, length of a single joint 0.02 to 0.03, breadth 0.04 to 0.05.
Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.
Genus 646. Lithomitra,[[263]] Bütschli, 1882, Zeitschr. f. wiss. Zool., p. 529.
Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with cylindrical shell, the upper pole of which is rounded, the lower truncate. Cephalis without horn.
The genus Lithomitra differs from the preceding genus Artostrobus in the absence of a cephalic horn, and therefore bears to it the same relation as Dictyomitra does to Lithostrobus. In many species the joints are very short, and bear only a single transverse row of pores, and since the constrictions between the joints are often very slight, Lithomitra becomes very similar to the Dicyrtide Dictyocephalus.
Subgenus 1. Lithomitrella, Haeckel.
Definition.—A single transverse row of small circular pores on each joint. (Sometimes on the uppermost joints two or three rows.)
1. Lithomitra pachyderma, Bütschli.
Lithomitra pachyderma, Bütschli, 1882, Zeitschr. f. wiss. Zool., Vol. xxxvi. p. 529.
Eucyrtidium pachyderma, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 21.