EARLY DEVONIC HISTORY OF NEW YORK AND EASTERN NORTH AMERICA \2'J 



nificent Uralichas ribeiroi Delgado, originally described from the 

 Lower Siluric of the Vallongo basin in Portugal and subsequently found in 

 the Ancrers schists of Western France as announced by Ochlert.' 



The latter writer attempting a reconstruction of the entire animal, con- 

 cludes that it attained a length of about 70 cm or 27!/^ inches. The great 

 tail spine on this magnificent species which in a pygidium figured by 

 Oehlert is not less than 6^ inches long, adds greatly to the actual length 

 of the tergum. Aside from this, it is likely that the former attained the 

 greater size ; at all events the Perce species makes an interesting addition 

 to the ranks of great trilobites which were specially predominant at this 

 early Devonic stage : Homalonotus major of the Oriskan)', H. col- 

 ossus Lake, of the Bokkeveldt beds of South Africa, D a 1 m a n i t e s 

 m y r m e c o p h o r u s of the Onondaga limestone, Terataspis grand is 

 of the Schoharie grit and Onondaga limestone, D. anchiops of the 

 Schoharie urit and D. tridens of the Helderbercrian. 



Locality. Found only in the Perce Rock. 



Dalmanites emarginatus Hall 



plate 7, futures 2, 3 



Dalmanites emarginatus Hall. Illustration of Devonian Fossils. 1876. 



pi. 10, fig. 2 

 Dalmanites (C o r o n u r a ?) emarginatus Hall (!c Clarke. I'alaeontology 



of New York. 1888. 7 140, pi. iiA, fig. 7, 8 



When this species was described our knowledge of it rested solely on 

 two small and like fragments of the posterior extremity of the pygidium, 

 both displaying the emarginate posterior border and the tubercled ribs. 

 These were both from the Schoharie grit of Schoharie, N. Y. The charac- 

 ters presented indicated a departure from the structure of the Dalmanites 

 pygidium toward that of species subsumed under the generic term Coro- 

 nura (Dal. m y r m e c o p ho r u s Green and D. diurus Green) in 

 which the emarofinate terminus is raised into an erect collar, from which 

 simple and compound spines extend backward. The New York rocks have 

 afforded no additional knowledi^e of Dalmanites e m a r o^ i n a t u s and 

 it is thus interesting to find this species present, so far as we can judge from 

 agreement in pygidial structure, and better presented in the Grande Grfeve 

 limestones. We have some nearly entire pygidia of large size, broadly sub- 

 triangular in outline with narrow and spineless border, retreating at the 

 posterior extremity in a broad curve to the apex of the axis. The pleurae 



' See Delgado, Descripcao de uma forma nova de Trilobite, Lichas (Uralichas) 

 Ribeiroi, 1892; Direccao dos Trabalhos Geolog. de Portugal; and Fauna Silurica de P/)rtu- 

 gal; Novas observacoes acerca de Fichas (Uraliclias) Ribeiroi, Fisbon, 1897; also Oehlert, 

 Uralichas ribeiroi des Schistes d'Angers; Memoires de la Soc. Geol. de France, 1896, 

 no. 16. 2, 



