L62 C. D. WALCOTT — DISCOVERY OF SILURIAN VERTEBRATES. 



GASTEROPODA. 



Metoptoma, sp. andet. Murchisonia, •"> sp. undet. 



Helicotoma planulata, Salter. Subulites (J), sp. undet. 



sp.? Bucania bidorsata, Hall. 

 Trochonema beachi, Whitfield (?). " ZmeZft, Whitfield. 



Murchisonia milleri, Hall. Cyrtolites, sp. undet. 

 pagoda. Salter. 



CEPHALOPODA. 



Orthoceras annellum, Conrad. Endoceras proteiforme, Mall. 



junceum, Hall. Gomphoceras, sp. ? 



CRUSTACEA. 



1. 1 perditia, sp. ? 



TRILOBITA. 



Ceraurus icarus, Billings. Asaphus platycephalus, Stokes. 



sp. ? '• megistos, Locke. 



Bathyurus (J), sp. undet. Tllsenus milleri, Billings. 



/Vo,Mx (/). S p. ? 



Summary. 



., . , Siiirns 



< n in I'll. Sni rn s. ■ i . . , 

 ' identified. 



A.ctinozoa i> '•' 4 



( Jrinoidea 1 1 < > 



Brachiopoda 6 12 11 



Lamellibranchiata 4 LO 5 



Gasteropoda 7 13 i> 



( lephalopoda 3 4 •"> 



Crustacea 1 1 



Trilobita 5 7 4 



Totals 33 57 33 



This fauna is distinctly of a Trenton facies, but as a whole it is upper 

 Trenton or Lorraine rather than lower Trenton. 



Recapitulation. — On assembling the faunas of the three fossiliferous 

 zones, the distribution of genera and species is found to be as follows: 



, , o • Sjtirii S 



Genera, opecies. ■ , ,->■ , 

 ' identified. 



Harding Sandstone 11 19 6 



Fremont Limestone (lower portion) 34 55 27 



upper portion) 33 7,7 33 



78 131 66 



Recurrent 28 10 10 



Total fauna 50 121 56 



