40«» PALAEONTOLOGY OF NEW-YORK. 



Fig. 7. The abdominal articulations, and the postcrio* spine, separated from the thoracic 



rings. 

 Fig, 8. An imperfect caudal spine, with the last two articulations of the abdomen. 

 Fig. 9. The caudal spine : a lateral view of a specimen not quite entire. The leftband is the 



dorsal side, and the general form is triangular, becoming more convex on each 



side of the dorsal edge towards the base. 



Fig. 10. The ventral side of a fragment, showing, on the Icfthand side of the figure, at a, the 

 articulation of one of the swimming feet, with the large maxillary joint, which 

 is nearly in its natural position, while the opposite one is displaced. The basal 

 articulations of the anterior feet are likewise seen more distinctly than in any 

 other specimen : the first and second are broken off, while the third is nearly 

 entire, and preserves the minute spines on the lower side of each joint. 



Fig. 11. A fragment showing the inner side of several of the thoracic articulations, and 

 preserving the anterior feet nearly entire, with the articulations of one of the 

 '' swimming feet : the place of attachment of these is obscured by some of the 



plates of the body below. 



Fig. 12. The post-oral plate of this species. 



PLATE LXXX A. 



Fig. 1. The ventral side of an imperfect specimen preserving the thoracic segments and four 

 of the abdominal joints, with the impression of one of the swimming feet entire, 

 and the other with the penultimate joint separated. Impressions of the maxillary 

 plates remain, showing their original form, as also the form of the post-oral plate. 

 The bases of the four anterior pairs of feet still remain, showing the place of 

 their origin. 



The last joint of the foot appears in this individual to slide over the triangular 

 piece of the preceding joint upon the lower side, which is not true : this ap- 

 pearance arises from the fact that it is a mould of the upper or dorsal surface 

 of this organ. 



Fig. 2. A part of the head of this species, showing part of the three first feet, while the 

 fourth is entire. 



Fig. 3. A dissected swimming foot, showing its attachment to the maxillary plate, the form 

 and proportions of the joints, and mode of articulation. 



Fig. 4. The broad terminal joint of the swimming foot, showing the notch at the extremity 

 and the small terminal palette. These separated joints are of not unfrequent 

 occurrence in strata where the Eurypterus is found. 



Fig. 5. A transverse section of the abdominal portion of one of these fossils : the section is 

 oblique to the body, and the appearance indicates that it has suffered little from 

 compression. This is the only evidence observed, which shows the original form 

 of the body. 



Fig. 6. A fragment of a crustacean associated with the E. remipes at Waterville, the rela- 

 tions of which have not been determined. 



PLATE LXXXIII B. 



Fig. 2. The carapace and three articulations of the body of E. remipes, for comparison with 

 the form of carapace of E. lacustris on same plate. 



'" Geological position and localities. In the Waterlime group at Waterville in the 

 town of Westmoreland, Oneida county; and at Wheelock's hill, Litchfield, Herki- 

 mer county, New-York. 



