44 BRITISH FOSSILS. 



Fig. 1 shows this plate in its natural position, and fig. 10 a 

 detached plate as commonly found. The latter occurs in a group 

 with a pair of antenna?, of which fig. 6 is one, and with the swimming 

 foot, fig. 8 ; all probably therefore belong to the same individual. 



Our specimens are so much altered in shape by pressure, that it is 

 difficult to point out any real variations in form. Fig. 2 appears 

 to have the true general shape. Fig. 1 is evidently compressed 

 laterally, as is the caudal joint, fig. 11 ; while fig. 12 shows that 

 joint shortened by pressure from behind forwards. Fig. 4 is 

 reduced in length by the same cause, and appears too broad in 

 proportion for the length. 



Locality. UPPERMOST LUDLOW BEDS, Lesmahago, Lanarkshire, 

 with several other species, and the shells Platysckisnia (Trochus) 

 helicites and Lingula cornea. All in the Museum of Practical 

 Geology. Collected by Mr. Robert Slimon. 



