PLATE 84 A. 



Fig. 1 & 2. Eestoration of the form and appendages of Eurypterus remipes. 



The parts represented are not in any respect imaginary, but have all been seen in different 

 individuals or parts of individuals, and are known to have the relations here expressed. 



Fig. 1. A dorsal view. The parts and surface-markings have been described in reference to figures 

 of preceding plates. 



Fig. 2. The ventral side, showing the position of the mouth and oral appendages, the two swim- 

 ming feet, the postoral plate, and the organ before referred to as a locomotive appen- 

 dage, but which I suppose may have borne the generative organs, as in the similar 

 appendage of Limui.us, and of other crustaceans, upon the corresponding segment of 

 the body. 



Fig. 3. Sapphirina gemma, after Dana. 



Fig. 4. A figure showing the mouth and bases of the feet of a female LiMULUS, the two 

 anterior tentacles, etc. 



Fig. 5. The membranous leaflet placed posteriorly to the mouth in Limulus, and regarded 

 as the anchylosed sixth pair of feet. The posterior extremities probably perform the same 

 functions as the extremities of the appendage behind the postoral plate in Eurypterus. 

 See Note, page 399. 



Fig. C> & 7. Plattonichtjs ocellatus. 



A representation of the upper and lower sides of one of the hinder or swimming feet (the 

 fifth pair) of this crustacean, which is a common species upon our coast, for comparison 

 with the corresponding pair in Eurypterus. 



