xlviii 
SYNOPSIS OF GENERA. 
1874. 
1875. 
1876. 
1876. 
1878. 
1878. 
1879. 
1881. 
1880. 
1884. 
1884. 
1885. 
1885. 
1885. 
1886. 
1886. 
Cypliaspl^, Steinhardt. Die bis jetzt in preuss. Geschieb. gef. Trilob. 
Cypha.'ipis, Maurer. Neues Jahrb. fiir Min. 
Cyphaspis, C. F. Rcemer. Lethsea palseozoica. 
PMllipsia? {B7'achymetopiis?). Hall. Illustrations of Devonian Fossils. 
Cyphaspis, Kayser. Faun. aelt. Devon. Ablag. des. Harzes. 
Gonloplewa, Angelin. Palieontologia Scandinavica. 
Cyphaspis, Hall. Twenty-eighth Kept. N. Y. State Mus. Nat. History. 
Cyphaspis, Hall. Eleventh Ann. Kept. Geol. Surv. Indiana. 
Cyphaspis, White. Second Ann. Kept. Geol. Survey Indiana. 
Cyphaspis, Ci.arke. Neues Jahrb. fiir Min. 
PhilUpsiaf, Cyphaspis, Walcott. Palaeontol. Eureka District. 
Cyphaspis, Clarke. Geol. Succession in Ontario Co. 
Cyphaspis, Maurer. Fauna der Kalke von Waldginnes. 
Cyphaspis, Zittel. Handbuch d. Palaiontologie. 
Cyphaspis, Maurer. Fauna d. rechtsrh. Unterdevon. 
Cyphaspis, Barrois. Ann. de la Soc. g6ol. du Nord. 
Diagnosis. Cephalon semicircular; genal 
angles produced into long spines. Glabella 
strongly arched, short and narrow, with two 
small pyriform basal lobes, bounded on all 
sides by deeply impressed furrows. Anterior 
lateral furrows obsolete. Cheeks broad, gran- 
ulose; eyes small, semilunate. Facial sutures 
beginning near the genal angles, and in front 
of the eyes diverging to the frontal margin. Thorax composed of from ten to 
seventeen segments, which are rounded at their extremities. Pygidium semi¬ 
circular, bearing from two to eight annulations upon the axis. 
XIPHOSURA. 
Family, Limulid.®. 
Genus PROTOLIMULUS, Packard. 1886. 
1885. Prestioichia, H. S. Williams. Amei-. Joui-. Science. 
1886. Protolhnuhbs, Packard. Mem. Nat. Acad Sciences. 
Diagnosis, Cephalothorax relatively large, sub-semicircular, genal angles 
produced. Cephalic appendages small; terminal segments of the posterior 
members foliaceous. Abdomen composed of six (?) segments, including the large 
caudal spine. 
