26 



Of the first anterior foot, this specimen shows only two joints 

 rather indistinctly ; the second is represented by six joints ; the 

 third by seven ; the fourth is complete, and exhibits eight joints 

 and a terminal spine like Eurypterus. The first three feet are 

 alike in structure and strength ; four short basal joints, of which 

 the second, the longest, is only about twice as long as its width, 

 measure together one inch in length. The fifth and sixth joints 

 of the second foot are each one inch long ; the fifth is 3-32, and 

 the sixth 1-16 inch broad. The first six joints of the third foot 

 are like those of the second foot ; its seventh joint has a length 

 of 7-8 inch and a width of a little less than 1-16 inch. The 

 fourth foot is more strongly developed than the other three ; its 

 basal joint is strong and almost oblong, about 5-8 inch long and 

 7-16 inch wide; it carries on its interior margin several long, 

 strong teeth. The second joint is a little shorter than the first 

 and tapers a little exteriorly ; the third is very short, only half 

 as long as wide ; the fourth is as long as the second, but only half 

 as wide and tapers toward the outer end ; the fifth joint is a trifle 

 longer, increases again at its exterior end to the width of the 

 interior margin of the fourth ; its length is a little more than 3-4 

 inch; the sixth joint is almost twice as long as the fifth, 1 3-8 

 inches, and throughout half as wide as the exterior margin of 

 the fifth ; the seventh joint is only 3-4 inch long and but little 

 more than half as wide as the sixth ; the eighth joint is about 

 two-thirds as long as the seventh and correspondingly narrower. 

 The terminal spine is triangular and about one-third as long as 

 the eighth joint ; it has for its base the whole width of this joint, 

 and tapers gradually to a sharp point. The total length of the 

 fourth foot is 5 3-8 inches. 



The swimming foot has been displaced, but shows eight joints 

 very clearly. (B. B. S. N. S., Vol. iv., p. 17.) Its basal margin is 

 armed with strong teeth, which decrease in size posteriorly ; the 

 rhomboidal plate is, like the whole appendage, comparatively 

 smaller than that of Eurypterus ; the second and third joints are 

 short and strong ; the fourth and fifth are almost twice as long 

 as the preceding ones and articulate to each other by strong 



