TO GEOLOGY. 37 



GENUS SERPULA. 



S. ornata. Plate 1. Fig. 5. 



Description. Shell granulate, below furnished with 

 three squamose carinse. 



Observations. Having a single specimen only of this spe- 

 cies, it is difficult to decide on its characteristics. The 

 beautiful granulations which cover the superior part, and 

 the squamose carinee will, I presume, be usually if not al- 

 ways found to exist on it. The form, however, of different 

 individuals will most likely differ. The one above described 

 takes one turn to the right, then three to the left, forming a 

 disk, the inferior portion being widely umbilicated. It has 

 some resemblance to the granulata (Sowerby), but differs in 

 having carinse. 



Of the twenty-seven species found in England, two 

 only have been discovered in the London Clay. The 

 genus seems to have prevailed more extensively in the 

 chalk and inferior formations. Five species are described by 

 Lamarck, and chiefly from Grignon. In the Upper Green 

 Sand of New Jersey and Delaware, Dr Morton has found 

 one species. In the Tertiary of Maryland, Mr Say observed 

 one, the granifera. 



