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PROCEEDINGS OF WASHINGTON MEETING. 



Maryland), 52 in North Carolina, and 13 in New Mexico and Arizona. Of course, 

 many of these species occur in more than one of these areas, the extent of the over- 

 lapping amounting to 43 species, or a little over one-third. "We thus learn that 85 

 of the 119 species, or considerably over two-thirds, are confined to one basin — in 

 fact, to one state or territory. So far, therefore, as the question of distribution or 

 parallelism within the United States is concerned, these 85 species are of no value, 

 and our present discussion must be confined to the remaining 34 species which are 

 found in two or more of these localities. 



Considering these 34 species, we find that there are common to the Connecticut 

 valley and to the New Jersey and Pennsylvania area, 5 species ; to the Connecticut 

 valley and the Virginia basin, 5 species ; to the Connecticut valley and North Caro- 

 lina basin, 6 species ; to the Connecticut valley and great Western basin, 1 species ; 

 to the New Jersey and Pennsylvania area and the Virginia basin, 7 species ; to the 

 New Jersey and Pennsylvania area and the North Carolina basin, 10 species ; to the 

 New Jersey and Pennsylvania area and the great Western basin, 2 species ; to the 

 Virginia and North Carolina basins, 20 species ; to the Virginia and Great "Western 

 basins, 2 species ; to the North Carolina and great "Western basins, 2 species. 



These facts may be expressed in tabular form as follows : 



If, in order to avoid the repetition of the names, we number the basins from 

 north to south, that of the Connecticut valley being 1 ; New Jersey and Pennsyl- 

 vania, 2 ; the Richmond coal-field, 3 ; the North Carolina basin, 4 ; and that of the 

 far west, 5 : then we observe that there occur in the first, second and third basins 1 

 species; in the first, third and fourth basins, 1 species; in the second, third and 

 fourth basins, 3 species ; in the first, second, third and fourth basins, 1 species ; in 

 the second, third, fourth and fifth basins, 1 species, and in all of the five basins, 1 

 species. This last is the widely diffused Clieirolepis munsU ri. 



There has been no serious question as to the parallelism of the New- Jersey and 

 Connecticut valley deposits, and as only eight unsatisfactorily determined species 

 occur in Pennsylvania it is impossible to argue from so meager data. Again, the 



