No. 6.] J. W. DAWSON — SILURIAN FOSSILS. 337 



Phaco^js Cauda tus (or allied). 

 Dalmania, allied to D, micrnrns^ Hall. 



* D. Logani^ Hall. 



It will be seen that, while the majority of the species found in 

 the lower bed occur also in the upper, the latter is much richer 

 in species, and especially in those of the Upper Arisaig or Lower 

 Helderberg proper. It is also remarkable for its much greater 

 number of Lamellibranchiate shells and Trilobites. On the 

 other hand it presents no points of resemblance with the Oriskany 

 fossils which accompany the ore of Nictaux in the western part 

 of Nova Scotia.* 



The fossils above referred to are derived from the beds imme- 

 diately containing the iron ore deposits, or from the ore-beds 

 themselves. But in many parts of the district there are rich 

 fossiliferous beds, the relation of which to the iron ores is not so 

 manifest, though they obviously belong to the same great series 

 of deposits. From these beds I have obtained specimens of 

 nearly all the species above catalogued, and some others in addi- 

 tion. The most important of these latter are the following: 



Zaphrentis, sp. not determinable. 



MeristeUa didi/ma, Dalman. A well-known European Upper 

 Silurian species, plentiful in some beds on the East 

 River, but which I have not yet seen from Arisaig. 



Lingula sp. 



Rhynchonella transversa^ Hall (or allied). 



R. allied to R. acnfij^Ucata, Hall. 



R. equiradiata, Hall (or allied). 



Orthls midtistriata, Hall (or allied). 



* Atrypa ejnacerata, Hall. 



* Trematosplra Acadice, Hall. 



^ Goniophora cousimilis, Billings. 



* Grammjjsia Acadica, Billings. 



* Cl'idophorus concentricas, Hall. 



* C cicneatus, Hall. 



* Modiolopsis rhomboideaj Hall. 



* 31. suh-7iasutus, Hall. 



* Bucania trilohita. Hall. 



Bellerophon, allied to B. carinatus^ Sowerby. 



* See paper in this Journal, 1879, on ' Recent Papers on the Geology 

 of Nova Scotia.' 



Vol. IX. V No. 6. 



