238 Letter from Professor NicJwIson. 



not mentioning liis name in connection Avitli ConcJdcorites corrugatus, 

 I trust he will find no difficulty in believing that my omission to do 

 so was due to ignorance, and by no means to willful neglect. 



I remain yours faithfully, 



H. ALLEYNE NICHOLSON. 



[Professor Nicholson first described the genus Conchicolites founded 

 upon the species Conchicolites gregarms, and no doubt is entertained 

 about the generic and specific characters. He next described the Con- 

 chicolites corragatus, and if he was right in placing this species in the 

 genus Conchicolites, then there can be little dqid^t that the genus Ortonia 

 is a synonym, and should be stricken from the list of names. He 

 described the genus Ortonia, founded upon the species Ortonia conica, 

 and in his own language : " The validity, or the reverse of a genus, is 

 invariably tested by the first species of the genus which may have been 

 described." Now, this conica and cormgatns can not be distinguished 

 by generic differences, and it remains an open question whether or not 

 they belong to the same species. Furthermore, the fonica, corrugatus, 

 and minor, so far as differences have yet been ascertained, must be 

 placed in the same genus. 



The question first to be considered is whether or not the corrugatus 

 belongs to the genus Conchicolites. It certainly does in the opinion of 

 Professor Nicholson. It does in my opinion. By turning to pages 7 

 and 8 of the January number of this journal, the render can compare 

 the specific description with the generic, and no doubt he will arrive 

 at the same conclusion. If he has a specimen of the corrugatus and 

 compares it with the generic description, he will necessarily come to 

 .the same result. Such comparison and observation must be satisfac- 

 tory. 



The next thing to be considered is whether the conica, on which the 

 genus Ortonia is founded, is generically distinct from Conchicolites. Of 

 course it ciui not be so distinct unless it differs generically from the 

 corrugatus. Professor Nicholson says, it " is distinguished by the much 

 more complete mode of its attachment, and by the fact that the tubes 

 are never attached sociall}-, in clustered masses, growing side by side." 

 But the fact is that one species has about as complete and full attach- 

 ment as the other, diflTering possibly in the fact that corrugatiis attaches 

 at the point as well as at the side, while conica attaches only at the 

 side ; and that both species are alike in social habits, and found alike 

 in clustered masses. These are all the points of difference relied upon 

 by Professor Nicholson, unless he claims that the corrugatus is com- 

 posed of a succession of imbricated rings, the wider ends of which are 



