140 M<}.< (i ni Silurian Arisaig Series of Arisaig, .X.s. 



has a second low fold and often a second shallow sinus 

 on the post-umbonal slope. 



1 length 20-37 mm., width 9.5-17 nun. 



Horizon and locality: Common in the Mc'Adam forma- 

 tion, coast section, Arisaig, N. S. 



Tropinuculites, new genus. 

 (T/oo7m, carina or keel + Nuculites.) 



Nuculacea with the dentition and clavicle of Nucul- 

 ites Conrad, but differing from that genus in the pres- 

 ence of a carina from the umbo to the poster o-basal 

 angle. In the single species referred to this genus the 

 surface in front of the carina is covered by concentric 

 prominent ornamental striae, while posterior to it are fine 

 growth-lines only. 



Genotype: Nuculites (Orthonota) carinata Hall. 



• Family Modiolopsidae Fischer. 

 Genus Goniophora Phillips. 

 Cosmogoniophora, new subgenus. 

 (KoV/io?, ornament. ) 



This subgenus is erected to include those forms of 

 Goniophora Phillips with radiating stria?. They are 

 very common in the Devonian, but in the Silurian are 

 confined to the Arisaig Stonehouse fauna. 



Genotype: Goniophora bellula Billings. 



SCIENTIFIC INTELLIGENCE. 

 I. Chemistry and Physics. 



1. Complex Atoms. — As long ago as 1816, in the early days 

 of modern chemical philosophy, the theory was advanced by 

 Prout, an English physician, that hydrogen was the primordial 

 element, and that the atoms of all the other elements were com- 

 posed of multiples of the hydrogen atom, so that, consequently 

 the atomic weights were all exact multiples of that of hydrogen. 

 As our knowledge of atomic weights became more exact in later 

 times it became evident that there were many cases where Prout's 

 hypothesis in regard to the atomic weights was at least not far 

 from the truth. The question as to the real truth of this 

 hypothesis lias been one of the incentives to the work of deter- 

 mining the atomic weights with great care by many investiga- 



