1916. No. 10. 



THE LOWER CAMBRIAN HOLMIA FAUNA. 



21 



Description: This form is quite common in the Hohnia shales at 

 Tømten, but is invariably in a poor state of preservation. In the shale 

 itself we find only quite flattened specimens, or others preserved in faint 

 relief. The shell as a rule has disappeared, and in its place we find 

 merely a shining surface that is darker than the shale itself, and in con- 

 sequence is prominent. 



Form and size: None of the specimens that are to be found in 

 my material appear to be quite complete. The most perfect (Catalogue 

 No. 15, in, 3) is depicted in the text-fig. 4 c. It was discovered in a fresh 

 main excavation just close to the old locality. The younger and broader 

 part of the shell is al- 

 most straight, with ex- j;'; a iâ] b 

 tremely faint diverging 

 lateral margins, which 

 proceed thus towards 

 the apex oi the shell, 

 almost in the form of 

 ■an angle, to a straight 

 initial portion with more 

 marked angle of diver- 

 gence. The extreme 

 apex of the shell and 



the pedicle opening 



Fig. 4. Sketches ot specimens ol TorellcUa laevigata Lnrs . 



are lacking, but the ^^^ Holmi nov. var. with cross sections, a — g Specimens 



specimen convevs a from Hohnia shale at Tomten, h A small fragment from 



, ", sandy limestone at Tømten. X3. 



jgod idea ot the torm. 



Another, but more incomplete specimen is seen on plate I, fig. 2. The 



broader, straight portion there passes into the initial part with a more 



arched line. The dimensions will be seen in the following table: 



/ 



Specimen 1 Specimen 

 Cat. No. 15, Cat. No. 13, 

 III, 3 I XXVII, 433 



Total length 



Length of the broader and straighter portion 



Breadth at broadest end 



Breadth at transition to initial portion 



Length of initial portion 



Breadth of apex 



135 

 95 



0.4 



95 mm. 

 6 



35 

 03 



