362 ME. E. S. COBBOLB OX THE [vol. lxxvi,. 



Bb x : that is, from below the Olenelhis Limestone to the repre- 

 sentative of the JParadoxides-tessini Zone of Scandinavia. 



Htolithellus micans, var. pallides nov. (PL XXIV, fig. 23.) 



A form, which may he separated as a distinct variety, occurs at a 

 comparatively low horizon in the Lower Cambrian. It has a truly 

 circular section, a rather stronger rate of taper, and, so far as 

 known, is always straight. The surface is grey and dull, not 

 glistening ; it shows slight traces of stria of growth. The diameter 

 varies from "3 to 1*2 millimetres. 



Locality and horizon. — Comley, Lower Cambrian ; from the 

 Holm in horizon Ab 3 ; also doubtfully from horizon Ab 2 . 



Hyolithelles micans, var. robestes nov. (PL XXIV, fig. 22.) 



This variety is one of those forms that is easily distinguished 

 when seen and handled, but the special characteristics are very 

 difficult to describe in words. 



It is separated from the more typical forms of H. micans by its 

 usually larger diameter (3 to 5 millimetres), its more decided rate 

 of taper (about 1 in 30), and in that it only occurs associated with 

 a Paradoccides fauna. 



The outer skin is thin (?), phosphatic, and usually grey; in 

 addition, it frequently has a thick lining of calcite which, in one 

 case, where the tube is 3 mm. in diameter; is as much as '4 mm. 

 thick, and simulates an inner shell. Whether this lining represents 

 part of the original organism, or is a mineral deposit subsequent to 

 its death cannot at present be determined. 



Locality and horizon. — Comley, Middle Cambrian; from 

 horizons Ba, of the Paradoxides-celandicus Zone and Bb, at the 

 base of the Paradoxides-tessini Zone. 



Htolithellus (?) sejstuosus, sp. nov. (PL XXIV, fig. 21.) 



Type-specimen [1912]. 



This specific name is proposed for small, circular, phosphatic 

 tubes which are curved in more than one plane, have a dull grey 

 surface, and are not associated with any that can be referred to 

 S. micans. Only two or three fragmentary specimens have been 

 as yet found, and one of these shows distinct lines of growth, 

 evenly spaced along the tube. 



Locality and horizon. — The Cwms, near Comley, Lower 

 Cambrian : from the greenish-grey sandstone, OboleUa-rjroomi 

 Beds, horizon Ab r 



Salopiella, gen. nov. 



Diagnosis. — Small tubes with elliptical section and sub- 

 parallel margins; shell-structure calcareous (?), thin, and formed 

 of a number of closely-set, step-like annulations, which encircle the 

 tube and are reproduced on the interior. 



Genotype. — S. obJicpia, sp. nov. 



