103 



This interesting species seems best represented in Europe by A. Resemblance 

 coriacea of Linnarsson, but that species is of the Paradoxides Zone, 

 its umbo is further from the hinge line, and the cardinal features are 

 different. 



It will be noted that the supposed vascular trunks in this species, 

 Acrothele avia and Obolus (Palceobolus) Bretonensis are far removed from 

 the margins of the valves. 



ACROTHELE, sp. 



A species of this genus occurs in the flags of Division 2 (b ?) of the St. 

 John Group at a cutting on the Intercolonial R. R. at Long Island 

 passage, St. Andrew's Channel. The material is too imperfect to de- 

 termine the species. 



Notes on the following table. 



It seems quite probable that when the Acrotheles that have been 

 described from the Lower Paradoxides beds are compared, some of the fol- 

 lowing names may be found to be synonyms, there being five species 

 accredited to the Band c. But it is to be remembered that there are two 

 sub-zones in this band, showing considerable d fferences in the fauna. 

 To the lower sub-zone of Paradoxides lamellatus (c/. (Elandicus) A. 

 granulata and A. cf. coriacea are to be assigned, and to the higher or 

 sub-zone of P. eteminicus, the other three. 



As Mr. Walcott's species are referred simply to Lower Cambrian, one 

 cannot compare them closely with the others ; but it seems possible 

 that the one referred to A. subsidua may be some other species, as it 

 occurs with a different fauna than that of the original form, and 

 apparently, by the stratigraphy, should be much older. 



I have ventured to assign White's A. subsidua to the Peltura Zone, 

 because it appears to be the same with a species which occurs in the 

 Mt. Stephen Fauna ; this fauna contains an Ogygia and an Olenoides 

 with other forms which appear to indicate this as the lowest horizon to 

 which it should be assigned. White's species is said by Director Walcott 

 to occur with Asaphiscus and Olenoides, which also appear to be Upper 

 Cambrian forms.* 



Near the same horizon, or perhaps a little higher, would come Bar- 

 rande's A. incohans which occurs in the ' Fauna of Hof ' equivalent to 

 the Tremadoc Fauna. 



