160 

 BOOK NOTICES. 



" The Lower Silurian Lamellibranchiata of Minnesota." By E. 

 O. Ulrich. From Vol. Ill of the final report of the Geol. and Nat. 

 Hist. Survey of Minnesota ; pp. 475-628, June 16, 1894. 



This interesting contribution to the palaeontology of the Cambro- 

 Silurian or Ordovician Rocks of Minnesota contains many things of 

 interest to Canadian geologists. Several of the forms therein described 

 or referred to, occur in Canada or are closely related to Canadian 

 species, whilst the discussion of their generic relations is always a topic 

 of special interest to all palaeontologists. This memoir constitutes 

 chapter VI of the third volume of the final report of the Minnesota 

 Survey and opens out with a short excursus on the terminology used in 

 the text. The following forms occur in Canada and are described in 

 the text and figured under the following designations. 



1. Ambonychia bellistriata, Hall. 



2. " amygdalina, Hall. 



3. Byssonychia radiata, Hall (sp.) 



( = Ambonychia rndiata of authors.) 



4. Modiolopsis mytiloides, Hall. 



5. Cyrtodonta rugosa, Billings. 



6. " Canadensis, Billings. 



7. Vanuxemia inconstans, Billings. 



8. Matheria tenera, Billings. 



9. Whitella Hindei, Billings, 



( = Cyrtodonta Hindei, B.) 



10. " plebeia, Billings. 



( = Cyrtodonta plebeia, B.) 



11. Ctenodonta nasuta. Hall. 



12. " " var. robusta, Ulrich. 



13. " gibberula, Salter. 



14. " levata, Hall. 



15. " Logani, Salter. 



Genus Whiteavesia. On page 513 of this memoir Prof. Ulrich 

 proposes the genus Aciinomya to receive a number of species heretofore 

 classed under the general designation of Afediolopsis. The name 



