362 CALIFORNIA ACADEMY OF SCIENCES. 



PsEUDONiscus Nieszk., 1859; Archiv Nat. Liv-, Esth- u. Kurl., vol. 1, p. 

 381. Silurian. 



BuNODELLA Matt., 1888; Traus. Koy. Soo. Canada, vol. 6, p. 56. 



Silurian. 



LlMULID^. 



Belinurus Koenig, 1825; Icones Foss., Sectiles, pi. 18, fig. 230. 



Carboniferous. 

 Prestwichia H. W., 1887; Quart. Jour. Geol. Soc. London, vol. 23, p. 32. 



Carboniferous. 

 LiMCLUS Miiller, 1785; Entomostraca, etc., p. 124. (Triassic.) 



Protolimulus Pack., 1886; Mem. Natl. Acad. Sci., vol. 3, p. 150. 



Carboniferous. 

 Neommulus H. W., 1868; Geol Mag., vol. 5, p. 1. Silurian. 



PHYLLOCAEIDA. 

 I. Carapace Univalve. 

 I. Flat or slightly convex shield. 



1. Neither sutured nor ridged along the back. Notched in front. 



A. Posterior border entire. 



DisciNOCARLS H. W., 1866; Quart. Jour. Soc. Geol. London, vol. 22, p. 504. 

 Round shield, angular notch. Middle and Upper Silurian (Murch.> 

 Aspidocaris Reuss, 1867. Triassic. 



Spathiocaris Clarke, 1882; Am. Jour. Sci., 3d series, vol. 23, p. 477. An- 

 gular notch. Devonian. 



PnoLADOCARiSi H. W., 1882; Geol. Mag. decade 3, vol. 9, p. 388. Sinuous 

 notch. Devonian. 



LisGOCARis Clarke, 1882; Am. Jour. Sci., 3d series, vol. 23, p. 478. 

 Oblong notch. Devonian. 



Ellipsocaris H. W., 1882; Geol. Mag., decade 3, vol. 9, p. 444. Rounded 

 notch. Devonian. 



B. Posterior border slightly notched. 



Cardiocaris H. W., 1882; Geol. Mag., decade 3, vol. 9, p. 386. 



C. Posterior border deeply notched. Devonian. 

 Pterocaris Barr., 1872; Syst. Sil. Bohfeme, vol. 1, suppl., p. 464. Both 



notches angular. Lower Silurian (Murch.) 

 Dipterocari.s Clarke, 1883; Am. Jour. Sci., 3d series, vol. 23, p. 121. Both 



notches angular. Cambrian. Devonian. 



Crescentilla Barr., 1872; Syst. Sil. Boheme, vol 1, suppl., p. 507. Both 



notches angular. Lower Silurian (Murch.) 



2. Ridged along the back. 



DiTHYOCARis (Scouler) Portl. ; Geol. Rep. Londonderry, etc., 1843, p. 313. 



Ridges sometimes prickly. Devonian and Carboniferous. 



Eachura Scudder, 1878. Only telson known. Carboniferous. 



