REPORT OF THE DIRECTOR I918 211 



a separate endognathite which distinctly shows the massive proximal 

 joints and the extremely slender, long, curved spines, five or more of 

 which are arranged in longitudinal series on each joint. The swim- 

 ming leg isasinEusarcus scorpionis, that is, of massive 

 proportions and furnished with a large paddle. The first to sixth 

 segments of the swimming leg are short, stout and provided with 

 finely interlocking articulations. 



The metastoma is subtriangular, heart-shaped, its width but little 

 smaller than its length. The frontal margin is emarginate, the 

 posterior part produced into a blunt lobe in a young specimen. 

 (See pi. I, fig. 6) 



Ornamentation. The ornamentation consists on most parts of 

 the body of extremely minute granules; on some parts, as the edge of 

 the metastcma and the postabdcmen, especially in larger specimens, 

 the granules develop into distinct disklike or lunate scales, like those 

 ofEusarcus scorpionis, and sometimes into elliptic, drop- 

 like scales as in Echinognathus. 



Measurements. The most perfect specimen has a carapace 27 mm 

 long and 35 mm wide at the base and 27.5 mm wide in front. The 

 greatest width of the preabdomen in this specimen is 44 mm, the 

 length of five tergites 40.5 mm. The compound eyes are 3 mm 

 long. In another specimen where the preabdomen is 38 mm wide, 

 the anterior end of the postabdomen is 24 mm wide and the 

 posterior end of the third postabdominal segment 10.5 mm. 



There is no doubt that Mixopterus multispinosus 

 reached a much greater length than the two bodies here figured, for 

 the second endognathite. which is the type of the species, is three 

 times as long as the corresponding part attached to the original of 

 plate I, figure 3, and we have before us a telson-spine, 23 mm wide 

 at the anterior end and originally at least i dm long. This would 

 indicate a specimen at least 4 dm, or considerably more than a foot 

 long. 



Horizon and locality. Vernon and Pittsford shale at Pittsford, 

 Monroe county, N. Y. 



Remarks. M. multispinosus has the snoutlike frontal 

 process of the carapace in common with Eusarcus vaningeni 

 Clarke and Ruedemann, E. cicerops (Clarke) and the Ordo- 

 vician types, E.nasutus and linguatus Clarke and Ruede- 

 mann. Of E. cicerops, specimens have been observed since the 

 publication of the Eurypterida of New York, that show the frontal 

 process much more pronounced than those figured in that work. 

 Although two specimens ofE. vaningeni were found with the 

 10 



