66 BRITISH FOSSILS. 



The sculpture is rather obscure, strong on the anterior half of 

 each segment, and faint over the rest ; the borders are smooth. 



Swimming Feet. These are the only appendages found with the 

 present species ; they resemble those of Pterygotus bilobus, and, 

 when laid back, reach the end of the fifth segment. The third 

 joint is very obscure ; the fourth trigonal with the longer side 

 outwards, and but little convex ; the fifth irregular, its produced 

 outer edge overhanging the oblong penultimate joint. 



This latter (cT) is about twice and a half as long as wide, rather 

 broadest at the bilobed end, the notch deep ; lobes rather acute, 

 the inner much exceeding the outer in size. Terminal palette ovate, 

 its length (measuring from the notch) equal to the penultimate 

 joint without the lobes. Margins minutely crenate. 



Locality. Lesmahago ; only one specimen known. (Museum of 

 Practical Geology.) 



