Correspondence — Mr» G, R. De Wilde. 533 



flint ; they are mostly arrow-heads with some knife flakes. I have 

 also a large round flattish hammer-head (with a round hole in 

 the centre), from the same locality, the weight of which is about 

 two pounds. James R. Gregory. 



ON EETEROPRYLLIA MIRABILIS, DUNCAN. 

 Sir, — In the Geological Magazine of this month (October, 1868), 

 Mr. John Young, speaking of Heterophyllia mirahilis, and J3. Lyelli 

 (as described by Dr. Duncan in the Transactions of the Royal Society), 

 suggests that the error, as he considers it, of representing the hook- 

 shaped processes attached to H. mirahilis as articulated, may have 

 arisen from the specimens examined being worn or indefinite. This 

 was not the case. The corals, which I believe were the property 

 of Mr. Thomson of Glasgow, were perfectly sharp and distinct. 

 The bulb or tubercle, with a pit in its centre, and the slight con- 

 cavity at the base of the booklet being too decided to admit of any 

 doubt or misconstruction. Besides, in nearly every case the booklets 

 had separated at the bulb. Supposing the articulation to be a mis- 

 take, these fragile appendages would hardly break invariably at that 

 point where they are stoutest and strongest. Yet in all specimens 

 that I have seen — and I have seen many — such is the rule. At the 

 time the plates for Dr. Duncan's paper were drawn I had been inti- 

 mately acquainted with corals, examining them day by day for a 

 space of six years, and the conviction is strong upon me that I must 

 have possessed sufficient discrimination to distinguish between a 

 fracture and an articulation. That a Zoophyte has no right to this- 

 articulation is a point about which 1 know nothing. Like other 

 creatures, it is possible they may occasionally exhibit eccentricities.^ 



G. R. De Wilde. 



ON HETEROPHYLLIA MIRABILIS, DUNCAN. 



1 have, at the request of my friend Mr. Henry Woodward, 

 very carefully examined, under the microscope, several specimens 

 of this curious coral (described by Dr. Duncan in the Philosophical 

 Transactions for 1867) forwarded to Mr. Woodward by Mr. John 

 Young, Under-Keeper of the Hunterian Museum, Glasgow. 



Not having seen the specimens figured by Mr. De Wilde in Dr. 

 Duncan's plate, I cannot venture on any positive assertion as tO' 

 whether or not those particular specimens have been rendered with 

 that artist's customary accuracy ; — but I have no hesitation in stating 

 that it is easy to select specimens from those sent by Mr. Young, 

 which present rows of tubercles, the exact counterpart of those 

 figured by Mr. De Wilde. 



On the other hand, however, there are amongst Mr. Young's 

 specimens, some which present characters diff'ering greatly from 

 those figured in Dr. Duncan's plate, and in which the booklets are 

 broken off at various distances from the costse — in some cases even 

 close up to the body of the coral, leaving a concave cicatrix instead 

 of a tubercle. 



