1438 THE VOYAGE OF H.M.S. CHALLENGER. 



larger circular pores, and three recurved, divergent, lateral wings of the same length. Third and 

 fourth joints each with three transverse rows of very large hexagonal pores. The similar form 

 described by Ehrenberg as Cydadophora davisiana, is either a mutilated specimen, or belongs to 

 Lithostrobus. 



Dimensions. Length of the shell (with four joints) 012, breadth 0'08. Length of the single 

 joints, a 0'02, 6 0'03, c 0-04, d 0'03. 



Habitat. North Atlantic, Greenland, depth 1000 to 1500 fathoms. 



5. Stichopilium campanulatum, n. sp. (PI. 77, fig. 11). 



Shell campanulate, with three slight strictures. Length of the four joints = 3:5:5:4. Cephalis 

 subovate, with an internal rod-cross, and a stout pyramidal horn of the same length. From 

 the middle of the collar stricture arise three divergent collar beams, which descend in the upper 

 half of the campanulate thorax as three divergent ribs, and are prolonged into three free horizontal 

 spines. (In the specimen figured these three wings are very short ; in another specimen, found after- 

 wards, there were three solid, pyramidal, horizontal spines, as long as the cephalic horn.) The third 

 joint is the broadest, of about the same length as the fourth. (The annular septum between the 

 two latter is by a mistake not figured). Pores subregular, circular, hexagonally framed. 



Dimensions. Length of the shell (with four joints) 017, breadth 012. Length of the single 

 joints, a 0'03, b 0'05, c 0'05, d 0'04. 



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



6. Stichopilium triserratum, n. sp. 



Shell slenderly campanulate, with three deep strictures. Length of the four joints = 2:4:6:3. 

 Cephalis hemispherical, with a stout pyramidal horn three times the length.. The three edges of the 

 horn are prolonged into three strong prominent ribs along the three first joints ; each rib bears a 

 series of stout, irregular, triangular teeth. The fourth joint is without ribs ; its constricted mouth 

 is half as broad as the third (broadest) joint. Pores subregular, circular. 



Dimensions. Length of the shell (with four joints) 015, breadth 0'08. Length of the single 

 joints, a 0'02, b 0'04, c 0'06, d 0'03. 



Habitat. Western Tropical Pacific, Station 225, depth 4475 fathoms. 



Subgenus 2. Stichopilidium, Haeckel. 

 Definition. Shell with four or more annular strictures and five or more joints. 



7. Stichopilium macropterum, Haeckel. 



Rliopalocanmm varietas, Bury, 1862, Polycystins of Barbados, pi. xvii. fig. 7. 



Shell slenderly conical, with five deep strictures. Length of the six joints = 2:5:4:3:3:6. 

 Cephalis hemispherical, with a stout conical horn of twice the length. Thorax campanulate, with 



