236 



Letter from Professor Nichohon. 



above low water-mark, under the bank of the Ohio river, in the first 

 ward of Cincinnati, below Mowry's car wheel works. They are also 

 found on the Kentucky shore, opposite the foot of Fifth street, and 

 opposite to and above the mouth of the Little Miami River. 



Fig. 29. — Biitholrephis ramulosus, showing the ends and the brandling stems as they appear 



on a nodule. 



The fossil is not known except in these indurated blue marl stones, 

 where it is found ramifymg them in every direction. Nor is it known 

 in the nodules of the same general character which are found in the 

 liigher rocks of the Cincinnati Group. 



It is a common fossil. 



Letter from Professor Nicholson on the Genera Conchieolites and Ortonia. 



University College, 



Toronto, March 30, 1874. 



S. A. Miller, Esq., 



Editor of the Cincinnati Quarterly Journal of Science: 



Sir — I observe an article by you in the first number of the Cincin- 

 nati Journal of Science, in which you criticise the genera Conchico,- 

 lites and Ortonia, founded by me, as well as some of the species of these. 

 I have not time at present to attempt to reply to the criticism at length, 

 but I trust you will allow me to make a few remarks upon two of the 

 points touched upon in your paper, and that you will give publicity 

 this letter in the next number of your valuable journal. 



