GYMNOSPERM.^:. 



99 



The certainty that it is quite distinct from the typical Podoearpus eocanica, in which 

 all the above-named specimens have been included, though perhaps erroneously, 

 and from any others hitherto described, necessitates a new specific name, and I have 

 therefore pleasure in naming it after the Duke of Argyll, to whose researches we were 

 first indebted for our knowledge of the flora. 



Detached leaves are not uncommon in the third or lowest bed at Ardtun. The fine 

 specimens on Plate XXVI are preserved in a close-grained matrix not unlike the 

 celebrated lithographic stone of Solenhofen, and are now deposited in the British 

 Museum. 



Ginkgo adiantoiues, Un(/er. Plate XXV. 



Ginkgo eiloba, Procacc. Annali di Bologna, An. 1°, vol. i, 209, pi. iv, fig. 3, 1838. 

 Salisburia adiantoides, TJnger. Synopsis, p. 211, 1845; Chloris Protogsea, 



p. Ixxvii, 1847 ; Gen. et Spec, p. 392, 



1850. 



— — Massal. e Scarab. Flora foss. del Senigalliese, p. 163, 



pi. i, fig. 1, pi. vi, fig. 18, pi. vii, fig. 2, 

 pi, xxxix, fig. 12, 1859. 



— Procaccinii, Massal. e Scarab. Id., p. 165, pi. xxxix, fig. 1, 1859. 



— BOREALis, Heer. Flora foss. arctica, vol. i, p. 95, pi. ii, fig. 1, pi. xlvii, 



fig. 4a, 1868. 



— ADIANTOIDES, Heer. Id., vol. i, p. 183, pi. 47, fig. 14, 1868. 

 Basaltic Formation ; Ardtun Head, Isle of Mull. 



Leaves from two to four inches in diameter, broadly fan-shaped or flabelliform, 

 somewhat resembling those of the Maiden-hair Pern, wedge-shaped at the base, 

 leathery, more or less cleft into two lobes, smooth, undulating, and sometimes notched at 

 the margin. Poot-stalk stout, equalling or exceeding in length the radius of the leaf. 

 The veins not only spring or diverge from the base, but also from two strong ribs 

 into which the petiole splits, and which border the lower sides of the leaf ; the veins 

 extend thence to the upper margin without diminishing in size, and are minute, dichoto- 

 mous, equi-distant, and sub-parallel, forking as often as necessary to maintain their relative 

 distances. Between these are quite disconnected, short, elevated, dotted, and spindle- 

 shaped regions, discernible in the fossil, and mistaken by Massalongo ^ for parasitic fungi. 

 These are best seen in the recent leaf by holding it to the light, when they appear trans- 



1 * Flor. foss. del. Senigalliese,' 1859, p. 87, pi. i, fig. 1, Sclerotites salisburice, Massal, Saporta has 

 suggested in a letter, and Mr. Murray of the British Museum has confirmed the view, that these are resin 

 chambers. They are referred to by Dr. Bary (' Vergleichende Anatomic,' English translation, p. 442) : — 

 " In the lamina of Ginkgo, in place of the uninterrupted canals, there are, between the vascular bundles, 

 short cylindrical sacs, 1 mm. or more in length, which are closed blindly at both ends." 



14 



