362 CALIFORNIA ACADEMY OF SCIENCES. 



PsEUDONisccrs Nieszk., 1859; Ai-chiv Nat. Liv-, Esth- n. Kurl., vol. 1, p. 

 381. Silurian. 



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



Silurian. 



LlMUI.ID^. 



Belinurus Koeuig, 1825; Icoues Foss., Sectiles, pi. 18, fig. 230. 



Carboniferous. 

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



Carboniferous. 

 LiMULus Miiller, 1785; Eutomostraca, etc., p. 124. (Triassic.) 



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



Carbouiferoiis. 

 Neolimdlus 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. 



DisciNOCARis 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. 



Pholadocaris 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. Bpheme, vol. 1, suppl., p. 464. Both 



notches angular. Lower Silurian (Murch.) 

 DiPTEROCARis 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 (Miirch.) 



2. Ridged along the back. 



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

 Ridges sometimes prickly. Devonian and Carboniferous. 



Rachura Scudder, 1878. Only telson known. Carboniferous. 



