NATURAL HISTORY SOOIEITY OF GLASGOW. 267 



tubercles are nothing but their broken bases. It was unfortunate 

 that Dr Duncan's specimens did not sliow these booklets, and that 

 he should have attempted to found specific distinctions upon frag- 

 ments, which every one wbo has had any opportunity of examining 

 this coral, will consider to have been imperfect examples of the 

 organism in question. 



Note. — I am glad to be able to state that since the date on which 

 this paper was read, Mr David Robertson has carefully examined, 

 under the microscope, all tbe specimens of this coral in the collec- 

 tion of Mr James Thomson, upon which Dr Duncan's figures and 

 descriptions were founded, and that, with a knowledge of all the 

 disputed points before him, Mr Robertson has failed to see any evi- 

 dence in these specimens of articulated booklets. Dr Young, who 

 has also examined Mr Thomson's specimens, confirms Mr Robert- 

 son's opinion, and says, that they present the same irregular fracture 

 of the booklets at their base as seen in our specimens — an appear- 

 ance not represented by any of the figures drawn by Mr De Wilde, 



EXPLANATION OF THE FIGURES OF PLATE IV. 



Fig. 1. — Ileterophi/Uia mirabilis. — Portion of a fiiifily-preserved specimen of the 

 coral, embedded in shale, showing several of the hooklets in position, 

 and the irregular way in which they have been fi-actured at various 

 distances from the stem of the coral by jjressure. From the collec- 

 tion of Mr James Armstrong. 

 Fig. 2. — Another specimen out of the matrix, showing the projecting bases of 

 several hooklets, and the very u-regular manner in which " they are 

 seen to be broken on many specimens of the coral. 

 Fig. 3. — Vertical section of a portion of one of the largest diameters of the 

 coral, in which the dissepiments are only one half line apart, or 

 about thirty in the length of one inch. 

 Fig. 4. — Vertical section of another sijecimen, in which the dissepiments are 



more wide apart. 

 Fig. 5. — Horizontal section, showing the normal form of the coral, and the 



septse and endotheca, when well preserved. 

 Fig. 6. — Horizontal section of a stellate, or six-sided angiilar variety. 

 Fif. 7. — Horizontal section of a nearly circular variety, in which the hooklets 



are planted in grooves on the stem instead of ujion costte. 

 Fig. 8. — Horizontal section of a four-sided or quadrangular variety, having only 



four septa corresponding to the number of costae. 

 Figs. 9, 10. — Triijonocarpwm (?). — A fossil fruit (natural size) from the, car- 

 boniferous limestone shales, Calderside, High Blantyre. Referred 

 to in Part I., page 203, of this Society's "Proceedings." 9, View 

 of calyx; 10, Side view of shell. 

 J^ote. — All the figures of the corals are enlarged from four to six times. 

 Fi"s. 2 to 8. are from specimens in Mr .J. Yomig's collection. 



