State Museu3i of Natural History. 25 



For tlie Bulletin upon tlie fossil Lamellibrancliiata, it was pro- 

 posed to illustrate the generic character of all known Palaeozoic 

 forms of this class. By the completion of the volumes on the 

 fossil Lamellibrancliiata of the Upper Helderberg, Hamilton, 

 Portage and Chemung groups, we have almost completely illus- 

 trated the Devonian genera and species of this class of fossils. It 

 is only necessary, therefore, to incorporate with these, in their 

 proper relations, the Cambrian and Silurian genera, in order to 

 present a complete synopsis of all the known Palaaozoic forms. 



As a preliminary to this Bulletin, the Report of the State 

 Geologist for 1882 was accompanied by illustrations of fifty-nine 

 genera, descriptions of which are published in the volume on the 

 Devonian Lamellibranchiata. 



To complete the work according to the plan originally proposed, 

 would require the study, description and illustration of about eighty- 

 four additional genera. 



I append herewith a list of the genera illustrated in the Report 

 of the State Geologist for 1882, together with a list of "described 

 genera not there illustrated, but which are necessary to the com- 

 pletion of proposed synopsis. Such a volume as here proposed 

 would form an important contribution to our knowledge, and 

 become a valuable text-book for reference both for amateurs, 

 students and authors. No similar work has ever been compiled in 

 any country, so far as I know, and heretofore our knowledge of 

 these organism would scarcely permit of such an undertaking ; but 

 the extensive contributions more recently made in this direction 

 are so great that we need no longer hesitate to give the results to 

 the public. 



I am, very respectfully. 



Your obedient servant, 



JAMES HALL, 



Director. 

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