REVIEWS — GEOLOGICAL SURYEY OF CANADA 275 



are glad to End that Professor Hall persists in the non-recognition 

 of the so-called genera Monograpsus, Diplograpsus, ^c. Although he 

 stands, in so doing, almost alone amongst palasontologists, every new 

 discovery tends to prove the justness of his views. 



The Report of Mr. Billings, although necessarily of limited popular 

 interest, will he fully appreciated by all engaged in the study of our 

 palaeontology. It comprises descriptions and figures of various new 

 genera and species of Canadian fossils, with a brief notice of Lake 

 Clear, in the newly surveyed township of Sebastopol, and an exceed- 

 ingly interesting essay on the Fauna of the Black River and Trenton 

 Limestones of Canada, as compared with, that of similar formations in 

 New York and Tennesee. Amongst the new forms, we have a remark- 

 able species of Obolus (0. Canadensis, Billings), two inches or more 

 across, from the Trenton (or Black River) limestone of the Fourth 

 Chute of the Bonnechere, Pauquette's Rapids, and from the townships 

 of Stafford and Westmeath, in the County of Renfrew. Also a new 

 genus of Braehiopoda named Eiehwaldia, by Mr. Billings, char- 

 acterised more especially by a perforation for the peduncle at the back 

 of the umbo of the larger valve ; and a new lamellibrauchiate genus 

 named Cyrtodonta. The latter, which is distinguished by the posses- 

 sion of three more or less curved anterior or cardinal teeth, (whence 

 the generic name,) and two or three lateral teeth (situated posteriorly^, 

 exhibits species from the Black River limestone, the Trenton lime- 

 stone, and the Hudson River group, respectively. The results of Mr. 

 Billings' comparative analysis of the fossils of the Black River and 

 Trenton beds of Canada, New York, and Tennesee, confirm the fact, 

 first shown by Sir William Logan in 1851, of a gradual passage of the 

 lower into the higher formation with us, whilst in the State of New 

 York a strong line of demarcation exists between the two. In Tenne- 

 see, on the other hand, there is a complete intermingling or rather 

 inversion of these forms ; some of the more highly characteristic Black 

 River types of New York, ( Columnaria alveolata and Stromatoceri- 

 um rugosum, for example,) occupying a higher position than the typical 

 Trenton forms.* For this reason, whilst retaining for special appli- 

 cations the subdivisions of Chazy, Bird's Eye, Black River, and 

 Trenton limestones, it is advisable in a general point of view to arrange 



* See Professor Stafford's paper " On the Silurian Basin of Middle Teunesee," in Silliman's 

 Jeurnal, 2nd series, vol. xii. p. 352,— quoted by Mr. Billings. 



