in the second, five in the third, six in the fourth, seven in the fifth, &c. (sometimes the increase of the number is more or less irregular). Horn of the cephalis strong, conical, straight, about as long as the fourth or sixth joint.
Dimensions.—Length of the shell (with six joints) 0.2; length of the fourth joint 0.04, breadth 0.06.
Habitat.—Fossil in Barbados.
15. Lithostrobus cuspidatus, Haeckel.
Shell, slender, conical, smooth, with straight axis, and ten to twelve distinct strictures. Joints gradually increasing slightly in length, the tenth twice as long as the third. Pores circular, in regular transverse rows; commonly two rows in the first, three in the second, four in the third, seven in the eighth and following joints. Horn of the cephalis long, bristle-shaped, curved. This species called Eucyrtidium cuspidatum by Ehrenberg, differs from Lithostrobus tristichus (compare above), to which Bailey had given the same name.
Dimensions.—Length of the shell (with ten joints) 0.2; length of the tenth joint 0.03, breadth 0.06.
Habitat.—North Atlantic (Greenland, Ehrenberg); Station 348, depth 2450 fathoms.
16. Lithostrobus cornutella, Bütschli.
Shell slender, conical, smooth, with straight axis, and seven to nine slight strictures. Joints gradually increasing slightly in length, the sixth or seventh about twice as long as the third. Pores circular, in regular transverse rows; two or three in the three or four first joints, three or four in the following, four or five in the last joints. Horn of the cephalis thin, bristle-shaped, curved.
Dimensions.—Length of the shell (with eight joints) 0.1; length of the eighth joint 0.01, breadth 0.04.
Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific; many stations, surface.
17. Lithostrobus tornatus, Haeckel.
Shell campanulate-conical, smooth, with straight axis, and four to six deep strictures. Joints broad, gradually increasing in length, the fifth twice as long as the second. Pores small, circular, in regular transverse rows; in the second and third joints three or four rows, in the fifth seven rows, &c. Horn of the cephalis small, double or forked.
