Correspondence — Professor J. Young. 583 



none. The testimony which that gentleman volunteers is, however, 

 of value as confirming the only inference possible from the state- 

 ments and figures, that the specimens of Heterophyllia are variously 

 preserved, and that Mr. De Wilde has not seen all the varieties. 



I am unaware, of course, of your reasons for adopting a somewhat 

 unusual style of comment on Mr. Young's paper. He does not, 

 however, as you say, '' object to a discovery because it is an anomaly." 

 He thinks the appearances may be otherwise interpreted, and that so 

 unexpected a phenomenon as articulated spines on a coral requires 

 more evidence in its support than has been adduced. Anomalies in 

 other groups of animals furnish no argument in support of this par- 

 ticular one. Mr. Young thinks his specimens justify him in taking 

 exception to Dr. Duncan's paper on two grounds, 1st, that H. Zi/ellisLiid 

 H. mirahilis are not distinct species, 2nd, that neither possessed arti- 

 culated spines. The criticism of published species is neither an un- 

 usual nor a hurtful proceeding, and I should have been unwilling to 

 interfere in the matter which rests entirely between Dr. Duncan and 

 Mr. Young, but that, having seen the specimens, I am satisfied that 

 the difference of opinion, at least on the second of Mr. Young's criti- 

 cisms, is due to difference in the state of preservation of the fossils. 



John Young, M.D. 

 HuNTERiAN Museum, Glasgow, 18^A November^ 1868. 



[Erratum. — In the heading to Mr. J. Young' sp aper on Heterophyllia (p. 448) 

 in our October Number, w€ styled him " Curator of the Hunterian Museum, Glasgow." 

 "We find we were in error. Professor John Young, M.D., is Keeper of the Museum, 

 and Mr. J. Young is Assistant-Keeper. — Edit.] 



BETEROPRTLLIA MIRABILIS, DUNCAN. 



Sir, — Having read, in the November number of the Geological 

 Magazine, the observations of Messrs. De Wilde, Fielding, and your- 

 self, upon the so-called articulation of the booklets on Heterophyllia 

 mirahilis, I now beg to state that the specimens of this coral which 

 I sent to you, and which are referred to in Mr. Fielding's remarks, 

 are of a mixed character, and were intended to illustrate the 

 various conditions in which it is found, such as the various diameters 

 the coral assumes, and the variation in form of the horizontal section. 

 Others show the rounding of the bases of the spines when worn, 

 presenting then the appearance of rounded tubercles ; while others 

 show the spines lying in position in the shale, or with their fractured 

 bases projecting irregularly from the stem of the corallum. 



The remarks which I formerly made were based partly upon 

 these and other longer specimens in my possession, and I am satis- 

 fied, after a further examination of all the best preserved specimens 

 I can find, that what I have stated in my paper is correct, viz., that 

 the booklets were not articulated upon tubercles, and the mere 

 rounding of the base of the spines, so as to resemble tubercles, seen 

 upon some specimens, stands for nothing in the face of the important 

 fact which numerous others go to prove, viz., that these tubercles are 

 not rounded in the better preserved specimens, and that they are in 

 fact only the fractured bases of the spines or booklets. 



