4I0* PALEONTOLOGY OF NEW-YORK. 



PLATE LXXXI B. 

 Fig. 1. A specimen of medium she, lying with the dorsal side exposed. The carapace has 

 boon broken off, showing the inner side of the maxillary plates, the post-oral 

 plate, and the four anterior pairs of feet, which are obscured at their bases. The 

 body is curved, and the tail-spine directed forwards. The pustuliform scales upon 

 the back arc in four rows on the thoracic joints, and two slightly diverging rows 

 on the abdominal joints. 



Fig. 2. The last joint of the swimming foot, with the minute palette at the extremity. 



Fig. 3. The seventh joint of the swimming foot, having the triangular chelate extension 

 separated at the suture. 



Fig. 4. The first articulation of the ventral side, with the organs attached. 



Fig. 5. A portion of the surface enlarged, showing the scale-like markings. 



PLATE LXXXIII B. 

 Fig. 3. The carapace of a large individual, showing the form to be distinct from fig. 2, which 

 is the carapace of E. rcmipcs. 



Geological position and locality. In the Waterlime group : Near Williamsville, 

 and near Buffalo, Erie county, New- York. 



Eui'jptcrus lacustris, var. robustus. 



Plate LXXXI C. Fia. L 



Carapace comparatively small. Body very robust, elongato-ovate. Joints 

 of the thorax broad and strong, their width being from four to six times 

 their length. Caudal segments increasing rapidly in length : terminal 

 spine unknown. The central locomotive appendage of the first joint of 

 the thorax is obsolete or imperfectly developed. The three anterior pairs 

 of feet strong and short-jointed, the first pair reaching little beyond 

 the margin of the carapace ; the fourth pair extending far beyond the 

 carapace : joints long, and thickened at the distal extremity ; postoral 

 plate oval-ovate, broader anteriorly and slightly emarginate in front ; 

 maxillary plates broad, rhomboidal. The second and third joints are 

 obscured ; the fourth, fifth and sixth are well preserved, and show the 

 prolongation of the anterior edges in short spine-like processes over the 

 next joint, which, exclusive of the soldered piece, is little longer than 

 wide : the eighth joint is oval-ovate, about twice as long as wide, 

 bilobed at the tip for the reception of the terminal palette, which is 

 small and scarcely exsert. 



