TRILOBITE HUNTING. 213 



There is another creature which has a distinct 

 likeness to some of the lowlier trilobites ; this is 

 the Bopyrus (Figs. 61, 62), 'a parasite of the shrimp. 

 As it is probable that all parasites are degraded 

 forms, it is regarded by some as not at all unlikely 

 that one branch of the older crustacean class, 

 possibly a section of the trilobite group, has found 

 its present resting-place in this diminutive parasitica 

 creature. The illustrations are of the female, which 



FlQ. 61. Shrimp Parasite FlG. 62. Shrimp Parasite 



(Ropyrus crangorum) (Bopyrus cranffontni) 



Upper side. Lower side. 



seems to be more degraded than the male, having 

 lost its eyes altogether, while the male preserves 

 them in a rudimentary condition. This has perhaps 

 arisen from the different habits of life which belong 

 to the female, and it is instructive to observe that 

 it is this more degraded form which most nearly 

 approaches the trilobite in appearance. 



Dean Buckland and others have regarded the 

 Serolis (Fig. 63) as being very closely related to 

 the trilobite. Certainly this creature has an old- 

 world look about it, and presents a remarkable 



