Shell spiny, everywhere covered with short conical spines. The upper conical part of the shell (with three joints) half as long as the lower cylindrical part (with six joints). Pores irregular, roundish, in the thorax twice to three times as large as in the eight other joints. Cephalis with a pyramidal horn of the same length. No longitudinal ribs. Dedicated to Heinrich Rathke (Königsberg, 1839).
Dimensions.—Length of the shell (with nine joints) 0.24; breadth of the third joint 0.08, of the fourth joint 0.06.
Habitat.—North Pacific, Station 253, depth 3125 fathoms.
7. Stichocorys mülleri, n. sp.
Shell in the upper conical part (with three joints) spiny, in the lower cylindrical part (with seven joints) smooth. Pores in the former irregularly scattered, roundish, in the latter circular, regularly disposed in longitudinal series, alternate, with prominent ribs. The upper conical part of the shell is about half as long as the lower cylindrical part. Cephalis with a large, pyramidal horn of three times the length. Dedicated to Johannes Müller (Berlin, 1858).
Dimensions.—Length of the shell (with ten joints) 0.22; breadth of the third joint 0.09, of the fourth joint 0.06.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
Genus 645. Artostrobus,[[262]] n. gen.
Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with cylindrical shell, the upper pole of which is rounded, the lower truncate. Cephalis with a horn.
The genus Artostrobus and the following Dictyomitra differ from all the other Stichocorida in the cylindrical or nearly cylindrical form of the shell, all the joints of which are nearly equal in breadth, and are very short, often with a single transverse row of pores only. The first joint or cephalis is usually different from the following, often hemispherical or cap-shaped joints. The last joint is truncate, and has a wide open mouth. Since the constrictions between the single joints are often very slight, some species are very similar to the Dicyrtide Sethocorys.