Kin PALEONTOLOGY OF NEW YORK. 



drawing which accompanies this description has been made from a plaster im- 

 pression of this natural mould. 



The cephalon in S. excelsior is more elongate, the anterior extremity narrower 

 and the orbital ridges very much more prominent than in any other known 

 species. It has an axial length of 252 mm., and a width of 223 mm., or a 

 length of about ten and a width of about nine inches. It undoubtedly repre- 

 sents one of the largest of palasozoic Crustacea, probably the largest known with 

 the exception of Pterygotus anglicus. By comparison with the other species of 

 Sti/lonurus, S. Logani, and S. Powriei, Woodward, of which the length is known 

 either from entire specimens or approximate restoration, it appears that & ex- 

 celsior would have measured, when entire, upward of fifty inches in length. 



Distribution. Catskill group. Andes, Delaware county. 



Stylon0rus(?) (Echinocaris?) Wrightianus. 



PLATE XXVII, FIGS. 7-9. 



Equisetides Wrightiana, Dawson. Quart. Jour. Geol. Soc, vol. xxxvii, p. 301, pi. xii, fig. 10; and pi. xiii, 



fig-. 20. 1881. 

 Equisetides Wrightiana (Dawson), Hall. Thirty-fifth Rept. N. Y. State Mus. Nat. Hist.: Expl. pi. xv. 



Note, and figs. 1 and 2, (Transmitted, 1882). 1884. 

 Echinocaris Wrightiana, Jones and Woodward. Geological Magazine, Dec. iii, vol. i, No. 9, p. 3, pi. xiii, 



figs. 1, a and b. 1884. 

 K<hiwearis Wrightiana, Etheridge, Woodward and Jones. Third Rept. Committee on Fossil Phyllopoda 



of the Pakeozoic Rocks, p. 35. 1885. 



Cephalothorax unknown. 



Abdomen. The original specimen consists of two somites, each being sub-cylin- 

 drical and flattened on the dorsal and ventral surfaces ; the anterior somite 

 somewhat the shorter and broader. The anterior margin of each somite is 

 elevated into an articulating ridge, which is shown to the best advantage 

 upon the posterior segment, as the overlapping edge of the preceding joint 

 lias been broken away in such a manner as to expose it. The dorsal and 

 lateral surfaces of each segment bear a series of sharp longitudinal ridges 

 which extend for nearly one-half the length of the segments. These ridges 

 themselves do not appear to have extended far beyond the posterior margins 

 of the segments, hut they may have served as the bases of attachment of 



