SYNOPSIS OF GENERA. xlvii 



than of Proetus, namely: the glabella is short and ovoid, with large, sub-pyri- 

 lbrni basal lobes distinctly separated from the body of the glabella, frontal area 

 broad and conspicuous. In the type species of Phaeton, however (Proetus 

 Archiaci and P. striatus, Barrande), the glabella is sub-quadrate or broadly conate, 



the basal lobes not separated from the glabella by the third lateral furrows, 

 while the two pairs of anterior furrows arc clearly visible. Angelin's genus 

 Phaithonides includes a well-defined group of trilobites allied in certain features 

 of the cephalon to Cyphaspis, and in certain features of the pygidium to Proetus, 

 but it appears very doubtful if this term can be used with propriety to cover 

 the species recognized by Barrande under the name Phut ton. Phaethonides 

 is represented in the American formations by four species, two from the Lower 

 Helderberg and two from the Devonian, and both cephalon and pygidium of 

 all these are known. A doubtful species is known from the Devonian rocks 

 of Nevada, which seems to be more closely allied to the Phaiton of Barrande 

 than to the Phaithonides of Angelin. Shall it eventually prove necessary 

 to separate the species originally included under Phaiton as generically distincl 

 from Phaethonides, recognition should be accorded to the term Prionopeltis, 

 Corda, 1847, which name was proposed for the same variations included under 

 the term Phaiton, Barrande. 



Genus CYPHASPIS, Burmeister. 1843. 



1843. Cyphaspis, Bi rmeister. Organ, der Trilobiten. 



1543. Calymene, F. A. Rcemer. Verstein. des Harzgeb. 



1843. Gerastos, Goldfuss. Leonhnrdt and Bronn's Neues Jahrb. fiir Min. 



1544. Phacops, C. F. Rcemer. Verstein. it. Rhein. Uebergangsgeb. 

 1S4T). Proetus, Lovex. Ofversigt. :if. Kcmgl. Vetensk. Akad. Forhandl. 

 1846. Cyphaspis, Geixitz. Grundr. der Verstein. 



1546. Cyphaspis, Barrande. Notice prelim, sur. Syst. Silur. 



1547. Cyphaspis, Conoparia, Gfoniopleura, Corda. Prodrom Monogr, bohm. Trilob 

 1850. Cyphaspis, the Brothers Sandbbrger. Verstein. d. Rhein. Schichtensyst. 

 1852. Cyphaspis, Barrande. Syst. Sil. Boheme, vol. i. 



1852. Cyphaspis. F. A. Rcemer. Beitr. ii zur Barzgeh 



1855. Cyphaspis, Sht.mard. Geol. Surv. Missouri. 



1855. Cyphaspis, F. A. Rcemer. Beitr. iii zur Hai'zgeb. 



1S5S. Cyphaspis, Giebel. Silur. Fauna (Jnterharz. 



1862. Cyphaspis, Hellmaxx. Die Petrefackten Thiiringens. 



1863. Cyphaspis, Hall. Trans. Albany Institute. 



1869. Cyphaspis, Haidexhaix. Zeitschr. der deutsch. geol. Gesellsch. 

 1872. Cyphaspis, Barrande. Syst. Sil. Boheme. vol. i, suppl. 



