FOSSIL LAMP-SHELLS. 223 



hardly distinguish the fossil Lingulas, found so abun- 

 dantly in the Lingula Flags (whence the name of the 

 latter deposit), from those still living, and possessed of 

 the same kind of peduncle or anchoring appendage, 

 as well as the same semi-horny structure of 

 shell. The pretty Terebratula striata, found 

 not uncommonly in the Chalk near Nor- 

 wich, is believed to be even specifically 

 identical with a form still living in British 

 seas, but known by another name. Mr. 

 Thomas Davidson, F.R.S., in his exceed- 

 ingly lucid papers on " What is a Brachi- 

 opod ?" published in the Geological Maga- 

 zine for 1877, says, "What wonderful 

 changes have been operating during the 

 incalculable number of ages in which the 

 creation and extinction of a large number 

 of genera and thousands of species have 

 taken place ! Some few only of the 

 primordial, or first created genera, such 

 as Lingula, Discina, and Crania, have 

 fought their way and struggled for exist- 

 ence through the entire sequence of geo- Fig. 189. z,/- 



. gular anatina, 



logical time : many were destined to a (recent), show- 



ing peduncle. 



comparatively ephemeral existence, while 

 others had a greater or lesser prolongation of repro- 

 duction." 



It seems as if the very name of this order contains 

 a fossil idea that these animals employed their long 



