414» PALEONTOLOGY OF NEW- YORK. 



The specimen consists of an imperfect carapace, with a part of the first joint of 

 tlie thorax remaining on one side, which is pustulose in the saTne manner as the 

 carapace. There are some intervals on the surface of the caraj)ace, between and 

 behind the eyes, where the pustules assume a somewhat scale-like form, similar to 

 the rows of scale-like pustules down the back of the animal. 



Fig. 1. The specimen, natural size. 



Geological position and locality. In the Waterlime group, near Buffalo. 



EijRYPTERUS, Subgenus Dolichoptervs. 



Cephauc, thoracic, and caudal portions of the body similar to Eurtpterus. 

 Postoral plate lyrate or cordiform-lyrate ; the central thoracic appen- 

 dage, from the first thoracic segment, strong, thick and simple in its 

 anterior part ; extremity ? Anterior feet composed of strong thick 

 joints, with curved terminal spines : posterior or natatory organs 

 having the joints elongate, the seventh and eighth little dilated, and 

 the terminal palette extremely developed. 



The principal differences from Eurypterus are in the development of the palette, 

 the less dilatation of the natatory feet, the form of the postoral plate, and the cen- 

 tral foot-like organ. 



Dolichopterus iiiacroclieirns ( n. s). 



Plate LXXXIII. Fig. 1 ; and Plate LXXXIII A. Fio. 1. 



Carapace seraioval, somewhat straight in front ; sides straight for more 

 than half the length from the base ; length and breadth about as 9 to 

 10. Eyes large, oval, distant, placed far forward and nearer the anterior 

 than the lateral margins of the carapace. Body elongate ovato-lanceo- 

 late, gradually contracting to the base of the first five joints, and more 

 abruptly below the sixth. The joints of the thorax are strong, and six, 

 or seven times as wide as long ; the ninth, tenth and eleventh segments 

 are proportionally much longer, the last one quadrangular. The margins 

 of the abdominal joints are but slightly imbricated. The anterior feet 



