SYNOPSIS OF GENERA. 



XX X 111 



■i. Hall, Illustrations of Devonian Fossils. 



('. F. Rckmkr. Lethsea palseozoicn. 



Kaysek. Abhandl. / Specialkarte Pr. und il. Thiir. St. 



•. Zeitschr der deutsch. geol. Gesellschaft. 

 Schlgeter. Sit/.ungsb. niederrb. Gesell. Bonn. 

 Katser. Jahrb. der Konigl. Preuss. geol. Lan lesanst. und Bergakad. 



hausen. Abhandl z Specialkarte Pr. und d. Thiir. S 

 Zittbl. Handb. d. Pateontologie. 

 Madrer. Fauna rechtsrhein. tlnterdev. 

 Matuschka Dachschiefer mrsr. 



Diagnosis. Genal angles produced into long, 

 often laterally compressed and narrow spines. 

 Posterior thoracic segments produced and acute. 

 Pygidium with five annulations and five pairs of 



marginal lubes or spines. Terminal lobe more or 

 less developed. 



Sub-genus DON TOO E P H A L U S, Conrad. L840. 



1832. Asaphns, Eaton. Geological Text-book. 



lSo'2. Ciili/iiinn . Green. Mon. Trilob. N. Americ 



1840. Odontocephalus, Conrad. Third Ann. Rept. Pal. N. V. 



IS42. Oa . Vanuxem. Geol Rept. Third Dist. N V. 



1843. ■ ephalus, Hall. Geol. Rept. Fourth l>i>i. N r . V. 



1845. Odontoci pita 'us, Kmmrich. Leonhardt and Bronn's Neues Jahrb. fiir. Miu. 



1861. Dai i'.n. Fifteenth Rept. N. Y. State Cab Nat. Hist. 



I8l 5. Odonti . Meek and Wohthen. Geol. Surv. Illinois, vol. iii. 



1^7'i. Dalmanites, Hall. Illustrations of Devonian Fossils. 



18S5. Odonto ■ . Zittel. Handb. a. Palseontologie. 



Diagnosis. The frontal border of the cepha- 

 lon bears a series of incisor-like denticulations, 

 which lie in contact at their distal extremities. 

 These are longest in front and become obsolete 

 about half way from the anterior extremity to 

 the tips of the genal spines. Pygidium usually 

 with two more or less developed terminal spines 



