282 Professors King and Rowney's 



extreme to the other, in this the most demonstrative example 

 we have yet met with, is without a break or interruption of 

 any kind. 



We iiave no doubt that Dr. Carpenter has often seen ex- 

 amples resembling the above ; but, considering that they are 

 called by him " pseudomorphs," considerable doubts may be 

 entertained of his being " perfectly acquainted with " them. 

 Be this as it may, he " freely admits their resemblance to cer- 

 tain forms of the acicular layer left after decalcification of the 

 nummuline layer." To us the resemblance is too close — of too 

 graduating a character to be dismissed in this manner. Dr. 

 Carj^jcnter wnll have, therefore, still to repeat — " Professors 

 King and Rowney persist in likening them, notwithstanding 

 my repeated assertions that the two things are altogether dif- 

 ferent"*. 



So, proofs of the complete passage of the " true nummuline 

 wall " into chrysotile or fibrous serpentine, and exhibited in a 

 highly metamorphosed rock with a complex mineral composi- 

 tion, are to be set aside by mere assertions, based on nothing 

 more than simulations, and made, too, by one who rightly 

 confesses that he is " not a mineralogist." 



It is quite unnecessary to bring forward any other cases 

 than those elsewhere made known f to show that the " num- 

 muline wall, in its t}^Dical condition, occurs in cracks or fissures 

 of the serpentine." It so happens that one of the cases re- 

 ferred to is seen in the section which has yielded the demon- 

 strations that have been described and figured. 



We have all along maintained that the " nummuline wall " 

 is an integral portion of the grains and other aggregations of 

 serpentine which it invests : hence, when a " constructed " 

 figure was continually being republished, and which, by repre- 

 senting the " wall " with two continuous bounding lines, made 

 it appear as a part independent of the skeleton, like the 

 chamber-roof of a Calcarina, we deemed ourselves called upon 

 to make known the objection we have to such representation. 



Specimens are abundant wdiich show the surfaces of the 

 grains gradually changing into the " nummuline wall," and 

 consequently proving the latter to be, not an independent part, 

 but an acicular variety of the serpentine. The specimens last 

 under consideration are evidences in point ; and we give, under 

 fig. 5, a representation of another specimen to sustain more 



* The italicization is ours. 



t See Quarterly Journal Geol. Society, toI. xxii. pi. xiv. fig. 4, p. 190: 

 Proc. Royal Irish Acad. vol. x. pi. xliii. figs, o, G. 



