CRUSTACEANS. 229 



Encrinurus deltoideus Shumard. 



Encrinurus delioideus Sh-um&Td, 1855 : Geol. Sur. Missouri, Ann. Rept., 



p. 198, pi. B, fig. 10. 

 Encrinurus {Cryptonynus'] deltoideus Vogdes, 1879: Mon. Genera Zethus, 



etc., p. 21. 

 Encrinurus deltoideus Foerste, 1887: Bui. Dennison Univ., vol. II, p. 102. 



Tail piece triangular, moderately convex, broadly curved 

 in front, rather sharply rounded behind. Median lobe sepa- 

 rated from the lateral lobes by deep furrows; segments rather 

 narrow, about twenty -four in uuml)er, all but the first five 

 somewhat blended above ; lateral lobes considerably wider 

 than the middle one; annulations eight, rather narrow at the 

 origin, but widening rapidly outward, and curving backward 

 and downward ; surface apparently smooth, though covered 

 with microscopic granules. 



Horizon and localities. — Upper Silurian, Girardeau lime- 

 stone : Cape Girardeau. 



Dalmanites tridentifera (Shumard). 



Plate xxxii, figs. 3a-b. 



Dalmania tridentifera Shumard, 1855: Geol. Sur. Missouri, Ann. Eep., 



p. 199, pi. B, figs. Sa-c. 

 Dahnanites tridentifera Meek & Worthen, 1868: Geol. Sur. Illinois, vol. 



Ill, p. 391, pi. vii, fig. 16. 



Cephalic shield rather low ; border rather wide, elevated 

 a little, with a broad shallow furrow running parallel to it 

 nearly the entire length; front extended into a conspicuous 

 three-pronged process, the ends of which are turned upward 

 slightly. Glabella moderately arched ; frontal lobe wider than 

 long, oval, or subrhomboid ; dorsal sinus rather deep. Eyes 

 very large, lunate. Pygidium moderately convex, produced 

 behind into a short spinous process ; median lobe made up of 

 about four annulations ; the lateral portions of about ten. 



Horizon and localities. — Upper Silurian, Delthyris shaly 

 limestone : Bailey Landing ( Perry county), Birmingham ( Cape 

 Girardeau county). 



