REPORT ON THE RADIOLARIA. 1481 



regularly disposed iu 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 Miiller (Berlin, 1858). 



JDimcnsions. — 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, n. gen. 



Definition. — S tichocorida (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. 



Subgenus 1. Artostrobulus, Haeckel. 



Definition. — A single transverse row of smaU, circular pores on each joint. 

 (Sometimes on the uppermost joints two or three rows.) 



1. Artostrobus annulatus, Haeckel. 



Comutclla annulata, Bailey, 1856, Amer. Joum. Sci. and Arts, vol. xxii. pi. i. fig. 5a, 5b. 

 Eucyrtidium annulatum, Haeckel, 1862, Monogr. d. EadioL, p. 327. 



Shell slender, cylindrical, smooth, without external strictures, but with ten to twenty internal 

 annular septa. On each joint only a single transverse row of small pores. Cephalis hemi- 

 spherical, with a single or double small horn. Each joint about four times as broad as long. 



Bimcnsims. — Length of the shell (with twenty joints) 0'2 ; length of each joint O-Ql, breadth 



0-04. 



jlabitat. — Arctic Ocean, Kamtschatka (Bailey) ; Greenland (Ehrenberg). 



1 Artostrobus = TiTea.A-coiie ; oi^rof, arjo'/Soj. 

 (ZOOL. CHALU EXP. — PART XL. — 1886.) Rl 186 



