Eucyrtidium anomalum, Haeckel, 1862, Monogr. d. Radiol., p. 323, Taf. vii. figs. 11-13.
Lithocampe anomala, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 839.
Stichopterygium anomalum, Haeckel, 1881, Prodromus, p. 439.
Shell five-jointed, with four internal septa, of a peculiar, irregular, and abnormal form. Cephalis small, hemispherical, with an oblique, curved horn. Thorax inflated, campanulate, with three large, latticed, and carinated protuberances. The third joint (the first abdominal joint) nearly as large as the thorax, two to three times as long as the two last joints, the septa of which are connected in a peculiar manner by a common nodal point on one side. Pores subregular, circular. (Compare the detailed description of this remarkable species—perhaps the type of a peculiar genus, Stichopterygium—in my Monograph, loc. cit.)
Dimensions.—Length of the shell (with five joints) 0.15, breadth 0.1.
Habitat.—Mediterranean (Messina), surface.
Genus 628. Pteropilium,[[245]] n. gen.
Definition.—Stichopilida (vel Stichocyrtida triradiata aperta) with three latticed external ribs or wings, without terminal feet. No horn upon the cephalis.
The genus Pteropilium (confounded by Ehrenberg with Pterocanium) differs from this three-jointed form by addition of new terminal joints. The shell-form is in general the same as in the preceding species, from which it may be derived by phylogenetic loss of the cephalic horn.
1. Pteropilium sphinx, Haeckel.