DISCI N oi AR I DM . 



SPATHIOCARIS, Clarke. 1882. 

 Spathiocaris Emersoni. 



PLATE XXXV, KIGS. 12-1S 



Spathiot arts Emersonii, Clarke. Araev. Jour. Science, Third Series, vol. xxiii. p. 477, pi. 0, figs. 1 -3. 1882. 

 Spathiocaris Emersonii, Packard. Monog. N\ Amer. Phyllopod Cru rwelfth Ann. Rept. U. S. Geol. 



., p. 451. 1883. 

 Spathiocaris Emersoni, Clarke. Neues Jahrb. Sir Min., etc., p. ISO. 1884. 

 SpatJiiocaris Emersonii, Ethbridoe, Woodward and Jones. Sei ond Rept. Committee on Fossil Phyllopoda 



of the Palaeozoic Rocks, p. 7. 1884. 

 Spathiocaris Etnerst nii, Jokes and Woodward. Geol. Mag-., Dec. iii, vol. i, p. 34S. 1884. 



Spathiocaris Emersoni, Clarke. Bull. U. S. Geol. Surv., No. 16. Higher Devonian Faunas. Ontari ninty, 



N. V.. p. 46. 1885. 

 Spathiocaris Emersonii, Etheridge, Woodward and Jones. Third Rept. Committee on Fossil Phj llopoda 



of the Palaeozoic Rocks, p. 3. 1885. 



Carapace ovate or elliptical in outline ; sin-race elevated and sub-conical, some- 

 what flattened on the posterior slope, more abruptly depressed at the sides. 

 The apex is situated somewhat anteriorly and connected by a low ridge with 

 the inner angle of the cephalic cleft. This cephalic or rostral cleft takes its 

 origin just in front of the apex of the shield and in uncompressed specimens 

 widens slowly outward. In flattened individuals the inner angle and the 

 width of this cleft are exaggerated. The surface of the shield is marked 

 by regular, continuous, closely appressed concentric ridges, following the 

 outline of the margin, becoming somewhat broader on the extremities and 

 crowded on the lateral portions. At the posterior extremity the surface 

 is cancellated by abundant radii, and similar radiating lines are visible in 

 the anterior region along the margins of the cephalic notch. The outline of 

 the carapace appears to vary with advancing growth, in mature individuals 

 being nearly elliptical, but in younger specimens appearing broader at the 



