1442 THE VOYAGE OF H.M.S. CHALLENGER. 



Dimensions. — Length of the shell (with sixteen joints) O'S, basal breadth 012. Length of 

 each single joint (on an average), 0'02. 



HaUtat. — Western Tropical Pacific, Station 225, depth 4475 fathoms. 



7. Artopilium stichopterygium, n. sp. (PI. 75, %. 8). 



Stichopterygiu7n tanypterum, Haeckel, 1881, Prodromus, p. 439, et Atlas. 



Shell slenderly ovate, subconical, with five deep strictures. The four lower joints are nearly 

 equal in length, each about twice as long as each of the first two joints. The fourth and fifth joints 

 are the broadest. Along the whole shell arise three broad, triangular wings, which envelop 

 the long, slender, pyramidal horn of the cephalis. In the delicate and loose lattice-work of each 

 wing is a longitudinal series of six large, ovate apertures, one on each joint. The small pores of the 

 shell are irregular, polygonal, or roundish. 



Dimensions. — Length of the shell (with six joints) 017, breadth 0'08. Length of each of the 

 four lower joints 0'03, of each of the two upper joints O'OIS. 



Habitat. — Central Pacific, Station 272, depth 2600 fathoms. 



8. Artopilium anomalum, Haeckel. 



Eucyrtidium anomalum, Haeckel, 1862, Monogr. d. Eadiol., p. 323, Taf. vii. figs. 11-13. 

 Litliocampe ano^nala, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 839. 

 Stichopiterygium anomalum, Haeckel, 1881, Prodromus, p. 439. 



Shell five-jointed, with four internal septa, of a peculiar, irregular, aud 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, he. cit.) 



Dimensions — Length of the shell (with five joints) 015, breadth 01. 



Habitat. — Mediterranean (Messina), surface. 



Geuus 628. Pterop>iliuin,'^ n. gen. 



Definition. — S t i c h o p i 1 i d a (vel Stichocyrtida triradiata aperta) with three 

 latticed external ribs or M'ings, 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. 



' PieropiKum = Winged hat ; •xTi^iv, x/Tkok. 



