82 THE ROYAL SOCIETY OF CANADA 



Page Line 



112, line 1 for "five," read four, and for "two" read one. 

 112 1 for "five" read, four, and for "two" read one. 



8, for "E.2 (a?)", read CIc. 

 116 to page 122, transfer to page 199 (at foot) 

 123 for "Etcheminian rocks" read Paradoxides beds. 

 132 transfer this page to page 199. 



148 to 151, as far as line 23, "obscured," transfer to page 213 at line 17. 



149 for "E2a," read CIc. 



174 HOLASAPHUS, page 175 and page 176 to line 3, transfer to page 232 line 17. 

 176 line 4, to line 23 transfer to page 223, line 10. 

 176 line 3 for "(E2a?)" read (CIc). 



179, from the table on this page, remove Lingulelle Selwyni, L. Roberti, Billings- 

 ella retroflexa, Holasaphus centropyge and Paradoxidoid trilobite. 



The transfer of the fossils of Young Point to the Paradoxides 

 zone, removes from the Etcheminian fauna several of the more ad- 

 vanced types of the Cambrian life zones that were thought to char- 

 acterize it. Although one trilobite remains, only the middle piece 

 of the head shield has been found and a free-cheek, &c. ; we have re- 

 ferred this head shield to Solenopleura, on account of its general form 

 but it is not a characteristic form of that genus, differing from it in 

 the long eyelobe and broad marginal fold. For this cause and on 

 account of its rarity it does not make a good horizon marker in the 

 Cape Breton Cambrian, and so we are thrown back upon the Brachio- 

 pods for the selection of a type that may be regarded as characteristic. 



The shells of this class are all Atremata or Neotremata. 



The two subfaunas of the Etcheminian of Cape Breton are dis- 

 tinguished by subgenera of Obolus which is among the common bi- 

 valves of this terrane. The older Eoobolus has the central group of 

 muscles far advanced in the valve, and there is a small scar, centrally 

 placed in the middle of this group of muscles, not found in Obolus 

 proper. In the more recent subgenus Palœobolus the central muscles 

 are also far advanced, but the vascular trunks are approximated, and 

 not spread apart as in Eoobolus. However, these markings on the 

 inner surfaces of the valves are not always discernable, and in such 

 case the differences from the Ordovician Oboli are not fully apparent. 



Perhaps the most characteristic among the Brachiopods of this 

 terrane is the little Acrothyra. This is a shell with a perforate beak 

 to the ventral valve, but differs from Acrotreta with which it is as- 

 sociated in the advanced position of the central muscles, which have 

 produced a long narrow callus extending half of the length of the valve. 

 Acrothyra, though it appears in the earliest Etcheminian strata of 

 Cape Breton island, does not reach its most characteristic form until 

 the latter part of Etcheminian time, when the beak and "callus attain 

 the unusually elongated form of the typical species. 



