XlVlll 



SYNOPSIS OF GENERA. 



1874 Cyphaspis, Steiuhardt. I>i'' l>is jetzl in preuss. Geschieb. get. Trilob. 



LS75. CypJiaspi . Hi rer. Neues Jahrb. fiir Min. 



1876. Cyphaspis, C. F. Rckmek. Lethaea palseozoica. 



1876. Phillips '). Hall. Illustrations of Devonian Fossils. 



ISTn. Cyphaspis, Kayser Faun. aelt. Devon. Ablag. des. Harzes. 



ls;s {, , a, Asoelin. Palseontologia Scandinavica. 



. II w.i.. Twenty-eighth Rept. N. V. State Mus. Nat. History. 



18SI. Cyphaspis, Hall. Eleventh Ann. Rept. Geol. Surv. Indiana. 



1880. Cyphaspis, Whim Second Ann. Rept. Geol. Survey Indiana. 



1884. Cyphaspis, Ci ihke. Neues Jahrb. fur Min. 

 18S4. PhUlipsia f, Cyphaspis, Walcott. Palseontol. Eureka District. 



1885. Cyphaspis, Clarke. Geol. Succession in Ontario Co. 

 l--:., Cyphaspis, Maursk. Fauna der Kalke von Waldgirmes. 

 1S85. Cyphaspis, Zittel. Handbuch d. PaUeontologie. 

 IS86 Cyphaspis, Maurer. Fauna d. rechtsrh. Unterdevon. 

 ISS6. Cyphaspis, Barrois. Ann. de la Soc. g-6ol. 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; eves small, semilunate. Facial sutures 

 beginning near the genal angles, and in front 

 of the eyes diverging to the frontal margin. Thorax composed of from 

 seventeen segments, which are rounded at their extremities. Pygidium 

 circular, bearing from two to eight annulations upon the axis. 



ten to 

 semi- 



XIPHOSURA. 



Family, Limulih.e. 

 Genus P ROTOLI M IT L U S, Packard. 1886. 



1885. Prestwichia, II. S.Williams. Amer. Jour. Science. 

 [886. Protolimwliis, Packard. Mem. Nat. A.cad Sciei s. 



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. 



