2IO NEW YORK STATE MUSEUM 



We are now also enabled to give a full description of the species 

 M. multispinosus (Clarke and Ruedemann) . 



Description. Body of small size, ovate-lanceolate in form, a 

 little more than three times as long as wide, broadest at one-third of 

 its length, moderately convex. 



Cephalothorax fairly large, occupying about one-fifth of the length 

 of the body. Carapace trapezoidal in outline, about one-fifth wider 

 than long (excluding the frontal process) , widest at base and contract- 

 ing to about five-sixths of its basal width by slightly converging, 

 somewhat concave lateral margins. Antero-lateral angles well 

 rounded; anterior margin extended into a rectangular snoutlike pro- 

 cess, about two-sevenths the anterior width of the carapace and twice 

 as wide as long. Its anterior margin is straight. The compound 

 eyes are small, but prominent, suboval in outline, situated at the 

 frontal margin, just outside the base of the protruding anterior pro- 

 cess. The ocelli are situated on a prominent circular mound, placed 

 one-third of the length of the carapace (excluding anterior process) 

 from the frontal margin. 



Abdomen. The abdomen is ovate-fusiform in outline; the preab- 

 domen about as long as wide, gradually widening to the fourth 

 tergite; its greatest width surpassing that of the cephalothorax by 

 only two-ninths ; thence contracting more abruptly to the postabdo- 

 men, which is slender conical, contracting in the first three segments 

 preserved to three-fifths of its original width. The tergites are broad, 

 short plates, the largest one is five times as broad as long; the " dorsal 

 furrows " are placed a little less than one-fourth the width from the 

 lateral margin. The sternites are relatively a little longer than the 

 tergites ; the operculum about four times as wide as long. The female 

 opercular appendage is shaped as in Eusarcus scorpionis, 

 extending to the middle of the postopercular plate and terminating 

 in two acute lobes. 



The telson is a slender spine, curved as in Eusarcus scor- 

 pionis ; and, as in that species, its basal portion is swollen globularly 

 on the ventral side. 



Appendages. Of the appendages of the cephalothorax, parts of 

 the walking and swimming legs, and the metastoma are preserved. 

 The type of the species consists of a fairly slender, first endognathite, 

 and the extremely long, powerful, second endognathite. The more 

 complete specimens from the Vernon shale, here figured, show these 

 two and also sufficient portions of the third and fourth endognathites, 

 to leave no doubt that the latter were considerably shorter and thinner 

 than the second pair of endognathites. Plate 3, figure 5, represents 



