246 THE PALEONTOLOGY OF MINNESOTA. 



LPrasopora. 



perhaps only at limited points, the interspaces left between them being occupied by 

 the small mesopores. These vary somewhat in number, and more so in size, but are 

 always decidedly angular. At intervals they are collected into substellate maculae 

 of greater or less extent, and in the immediate vicinity of these the zooecia are of 

 appreciably larger size than elsewhere. No evidence whatever of acanthopores has 

 been detected. 



In vertical sections the cystiphragms form continuous series on one or both 

 sides of the tubes, according as they extended all around the circumference or 

 embraced only a portion of same, while an equal number of straight diaphragms 

 crosses the remaining portion of the tube. In the Kentucky, Tennessee, and 

 Minnesota form of the species the tabulation of the tubes is more uniform and 

 crowded than in the Canadian and New York variety, for which the name 

 orientalis is proposed. In the former the cystiphragms average sixteen or seven- 

 teen in 2 mm., while in the latter the average does not exceed thirteen, and in 

 some cases is not over ten in that space. In the mesopores the diaphragms are 

 simple, and average about eighteen in 1 mm. for the typical form, and twelve for 

 var. orientalis. 



Variety ORIENTALIS, n. var. 



PLATE XVI, FIGS. 1,2, 6, 7. 



Monticulipora:\Diplotrypa) whiteavesi (part.) Nicholson, 1879. Pal. Tab. Corals, p. 316. 



This subordinate name is proposed for the eastern variety of the species. It is 

 distinguished from the typical form by the greater extent and distinctness ot the 

 substellate maculae, the greater size attained by the zoo3cia in the immediate 

 vicinity of the maculae and the less compact tabulation of the zooecia and the 

 mesopores. 



This species may really be the one referred to by Vanuxem in 1842 (Geol. 3d 

 Dist. N. Y. p. 46), when he speaks of "The Puff ball favosite (Favosites lycopodites)" 

 as being highly characteristic and in great numbers in the Trenton limestone of 

 New York. He adds, "it is found also in the lower part of the Utica slate, where it 

 ends," and that "it is equally abundant at Frankfort, Kentucky, where it received 

 the name of Trianisites cliff ordi." 



The name Favosites or Chcetetes lycoperdon (equivalent to Vanuxem's Favosites 

 lycopodites) is generally credited to Say, but no description . of the form was ever 

 published by him, and the first known of the so-called species under that name is 



