1508 THE VOYAGE OF H.M.S. CHALLENGER. 



20. Lithocampe heptacola, n. sp. (PL 79, fig. 8). 



Shell smooth, subcylindrical, constricted at both poles, with six distinct strictures. Seven 

 joints of different lengths, the five abdominal joints nearly equal, each half as long as the hemi- 

 spherical, vaulted thorax, and twice as long as the subspherical, small cephalis. Mouth constricted, 

 with a short, tubular, hyaline peristome (like an eighth joint without pores), about one-third as broad as 

 each of the four middle joints. Pores subregular hexagonal, or irregular polygonal, with thin bars. 



Dimensions. Length of the shell (with seven joints) 0'24, greatest breadth 0'09. Length of 

 the cephalis 0'02, thorax 0'06, each of the four following joints 0'03, of the last joint 0'04. 



Habitat. Central Pacific, Station 266, depth 2750 fathoms. 



21. Lithocampe octocola, n. sp. (PL 79, fig. 6). 



Shell smooth, subcylindrical, thick-walled, constricted at both poles, without distinct, external 

 strictures, but with seven internal septal rings. Eight joints of different lengths ; four joints (the 

 second to the fifth) being about twice as long as the four others (the first and the three last). 

 The constricted mouth only one-third as broad as the four middle joints. Pores small and 

 numerous, subregular, circular. 



Dimensions. Length of the shell (with eight joints) 019, breadth 0'09. Length of the second 

 to the fifth joints, each 0'03 ; length of the four other joints, each about 0'016. 



Habitat. Central Pacific, Station 274, depth 2750 fathoms. 



22. Lithocampe polycola, n. sp. 



Shell smooth, subcylindrical, constricted at both poles, with twelve to fifteen distinct strictures. 

 Fourteen to sixteen joints of- different lengths. Cephalis flat, cap-shaped, hyaline, without pores. 

 Thorax nearly hemispherical, with three transverse rows of small circular pores. Each following 

 joint (each abdominal joint) only with a single row of small pores. The constricted mouth of the 

 last joint only one-third as broad as the middle part of .the shell. (Very similar to Lithomitra 

 eruca, PL 79, fig. 3.) 



Dimensions. Length of the shell (with sixteen joints) 0'3, breadth 0'08. Length of the 

 cephalis 0'02, thorax 0'06, each of the following joints 0'015, last joint - 025. 



Habitat. Tropical Pacific, Station 224, depth 1850 fathoms. 



Genus 651. Spirocyrtis, 1 Haeckel, 1881, Prodromus, p. 438. 



Definition. Stich ocor id a (vel Stichocyrtida eradiata aperta) with spirally- 

 arranged constrictions on the shell. Cephalis with a horn. 



The genus Spirocyrtis and the following closely allied genus Spirocampe differ from 

 the other Stichocorida (and also from nearly all C y r t o i d e a) in a very remarkable 



1 Spirocyrtis = Spiral basket ; axtioa, nvfri's. 



