172 Notices of Memoirs — Dr. Matthew — Cambrian. 



IsTOOriCiES OIF- DVCEUVnOIIRS- 



T. — Additional Notes on the Cambrian of Cape Breton, with 

 Descriptions of New Species. By G. F. Matthew, LL.D., 

 F.E.S.C. (From Bulletin of the Natural History Society of 

 New Brunswick, Canada, No. xx, vol. iv, pt. 5.) 



fPHIS article deals with two subjects: (A) New Species of the 

 I Etcheminian or Basal Cambrian ; (B) The Tremadoc Fauna. 

 Under the first the development of the three perforate genera 

 Acrothyra, Acrotreta, and Acrothele is described. The two first 

 have been found in the lowest fossiliferous beds of the Basal 

 Cambrian ; from which they are traced upwai'd, the first to 

 Protolenus fauna (under Paradoxides) , the second into the Ordo- 

 vician. The first genus is specially prevalent in the Etcheminian 

 or Basal Cambrian beds, one species being found in the Lower and 

 another in the Upper Etcheminian beds. 



A point worked out in this article is the change in size and form 

 of Acrotreta as time went on. The first species known were about 

 twice as wide as high, but towards the close of the lifetime of the 

 genus the height and width were about equal, though in two species 

 the height exceeded the width. 



Acrothele was not found in the Lower Etcheminian, but comes in 

 with the Upper Etcheminian fauna. Various species are quoted, 

 ranging from this fauna to the top of the Cambrian. 



There are described in this paper, of Acrothyra one new species 

 and six mutations ; oi Acrotreta, one new species and two mutations ; 

 of Acrothele, two new species and one mutation. 



The second part of the paper relates to species of Gasteropods and 

 Trilobites recognized as representatives of the Tremadoc Fauna. 

 Asaphellus Ilomfrayi is cited, also a new species, A. (?) planus. 

 Species of Triarthriis, ParahoUnella, and Pellerophon were found, 

 also Lingulella and Acrotreta. 



Six plates of figures are given to show the forms and characters 

 of new species described. 



II. — On the Eelation of the Silurian and Ordovician Eooks 

 OF North-West Ireland to the Great Metamorphic Series. 

 By Jas. E. Kilroe and Alex. McHenry.' 



UPPEE Silurian rocks, as high as Wenlock, have been meta- 

 morphosed along the Croagh Patrick range, which led to their 

 inclusion in the great metamorphic group when the ground was 

 originally mapped. The corresponding rocks of Wenlock age on 

 the south margin of the Mayo and Galway Silurian basin, near 

 Killary Harbour, are not metamorphosed, and rest unconformably 

 upon the metamorphic group. 



This stratigraphical break has for many years been supposed to 

 form an insuperable objection to the acceptance of Murchison's 



1 Read before the British Asfsociation, Section C (Geology), Glasgow, Sept., 1901. 



