Shell slenderly conical, smooth, with straight axis, and eight to ten deep strictures. All joints nearly of the same length, the eighth joint twice as broad as the third. In each joint three transverse rows of pores. Horn of the cephalis bristle-shaped, strongly curved, about as long as the shell (Ehrenberg confounds this species with Lithostrobus cuspidatus).
Dimensions.—Length of the shell (with eight joints) 0.16, of each joint 0.02; breadth of the fourth joint 0.04, of the eighth 0.08.
Habitat.—North Pacific, Kamtschatka (Bailey); Station 241, depth 2300 fathoms.
4. Lithostrobus tetrastichus, n. sp. (Pl. [80], fig. 6).
Shell slenderly conical, smooth, with straight axis and six to eight deep strictures. All joints nearly of the same length, the eighth joint twice as broad as the second. In each joint four transverse rows of regular, circular pores with very thin bars. Horn of the cephalis conical, strong, curved, about as long as two joints.
Dimensions.—Length of the shell (with eight joints) 0.12, of each joint 0.015; breadth of the second joint 0.02, of the eighth 0.04.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
5. Lithostrobus pentastichus, n. sp.
Shell slenderly conical, smooth, with straight axis, and six to eight slight strictures. All joints nearly of the same length, the sixth twice as broad as the third. In each joint five transverse rows of small circular pores. Horn of the cephalis pyramidal, of twice the length. (Similar to Eucyrtidium cienkowskii, Pl. [80], fig. 9, but regularly conical, with all the joints equal in length.)
Dimensions.—Length of the shell (with eight joints) 0.2, of each joint 0.025; breadth of the third joint 0.04, of the sixth 0.08.