FOSSILS OF THE NIAGARA GROUP. 



427 



Fig. 13. 



This species somewhat resembles D. limulurus {Pliacofs Imulurus, Palse- 



ontology N. Y., II, Plate 67, fig. 1) ; but differs in the proportionally larger 

 glabella, the larger and more promi- p^^ j^ 



nent eyes, and the extension of the 

 anterior border. The pygidium is 

 less rounded on the anterior margin, 

 the spine is more obtuse, the flat- 

 tened margin outside of the ribs is 

 narrower, and the number of ribs on the lateral 



lobes is greater. In figs. 13 and 14, the head and pygidium of this 



species are represented. 



Geological Formation and Location. — In Niagara limestone, at Waukesha, 



Wisconsin. 



GENUS CERAURUS, Green. 



CHEIRURUS, Betrioh. 



Ceraurus NIAGARENSIS, N. S. 



plate xxi, figs. 10, 11. 



Compare Cheirurus insignis, BErRiCH. Ub. Bohm, Tril. p. 12, fig. 1. 



Compare Cheirurus insignis, Bakeande. Syst. Sil. du Centre de la Boheme, p. 782, Plate 41. 



Compare Cheirurus insignis, Corda. Prod., p. 133, Plate vi, fig. 70. 



Ceraurus insignis, Hall. Palasontology N. Y., II, pp. 300, 306, Plate 67, figs. 9, 10. 



Ceraurus insignis. Hall; in Twentieth Rep. State Cab., 1st edit., p. 335. 1867. 



A careful comparison of our specimens with the figures of C. insignis, 

 given by Barrande, shows certain difi'erences in the general form of the 

 glabella, the direction of the furrows and form of posterior lobes, which 

 I am inclined to regard as of specific importance, and therefore propose 

 another specific name. The New York and Wisconsin specimens of this 

 species preserve the same characteristics. 



In the collection loaned to me for examination by Prof Winchell, I 

 have discovered the hypostoma of a Ceraurus attached to the front of 

 an imperfect glabella, which I infer belongs to this species. This appen- 

 dage differs from the hypostoma of C. insignis in being more rounded 

 anteriorly, and not so deeply notched at the sides, while the border 

 just anterior to the notch is not expanded as in the European species. 



This species was, I believe, first identified with the European C. insignis 

 by M. E. DeVernbuil, in his memoir on the parallelism of the European 

 and American palaeozoic formations.* A comparison with the figures of 

 Beyrich then satisfied me that our species was identical with the Euro- 



* Bulletin Soc. Geol. de France, 1847. 



