Book Notices. 499 



C. Laurentiana and C. integriloha. The rest had been described 

 in previous Issues of the " Rhodora," or in other publications. 



The conjoint labours of Mr. Jack and Prof. Sargent in this 

 connection cannot fail to give a fresh impetus to the local 

 study of this interesting genus, especially as it is intimated 

 in this paper that there are probably other species in the 

 district remaining yet to be found and named. 



Prof. Sargenfs second pamphlet is of less interest to the 

 botanists of Canada, perhaps, but is of equal importance as a 

 contribution to the Natural History of this continent. In it 

 he describes thirteen species of Crataegus to which he calls 

 attention as " new or little known American trees." The 

 majority of these were found in the States of Arkansas, Mis- 

 souri and Texas, although one of them, C. pedicellata, is 

 credited to Rochester, N.Y. The special point of interest to 

 science in both brochures is the apparent sensitiveness to 

 environment of the Crataegus family. This group of plants 

 is now known to be represented by a much greater variety 

 than was formerly assumed. Whether they are all to be 

 counted distinct species or whether some of them are to be 

 regarded rather as crosses between species hitherto acknow- 

 ledged, it must be left to further observation in the future 

 to determine. 



Professor Sargent also describes in this paper, Betula 

 Alaskajsta, a new species of Rocky Mountain birch, nearly 

 allied to the Betida papyrifera of the east, and also Betula 

 occiDE]\'TALis HooKER of the Same region as well as a new 

 species of Cypress, Cypeessus pygm^ea, the habitat of which 

 Mendocino County, California. 



R.C. 



A Revision of the Genera and Species of Canadian 

 Palaeozoic Corals : The Madreporaria Aporosa and the 

 Madreporaria Rugosa. — By Lawrence M. Lambe, P.G-.S., Assis- 

 tant Palaeontologist. 



This is part of Vol. IV. of the Contributions to Canadian 

 Palaeontology, furnished by the Geological Survey of Canada 

 and published by the Government. It is an ideal work of its 

 kind which cannot fail to win for Mr. Lambe a still higher 

 reputation as a careful and skilful palaeontologist. In this 

 volume he has described ninety-five species and two varieties, 

 ninety-seven in all, embraced in twenty-four genera. The 

 localities in which these fossil corals were found, the dates 



