316 Meek — Shell-structure of Syringothyris, 



pened to examine chippings from specimens not in a condition to 

 show the punctures. I have likewise ascertained, since the publica- 

 tion of my former paper on this subject, that Spirifer propinquus, 

 Hall, and S. Sannibalensis, Swallow, both nearly like S. cuspidatus, 

 have a clearly punctate structure, and hence, probably belong to the 

 group Syringothyris. 



I have just read a letter from Mr. Davidson, written to Mr. 

 Worthen, in which he quotes, from a letter to him from Dr. Car- 

 penter, a paragraph giving the results of his examinations of speci- 

 mens of Syringothyris, and of the same Irish shell examined by me 

 (and at one time supposed to be Spirifer cuspidatus). These chip- 

 pings were sent over by Mr. Worthen, at Mr. Davidson's request, 

 some little time back. Dr. Carpenter says he finds the Syringothyris 

 (that from Floyd Co., Indiana, I suppose), distinctly punctate, the 

 punctures being, as I stated, small and scattering. The chippings 

 from the Irish specimen sent over to Mr. Worthen, with the name 

 S. cuspidatus attached, Dr. Carpenter also found to be punctured, 

 though the punctures are not so clearly seen as in the other. Chip- 

 pings of S. subcuspidatus, Hall, sent by Mr. Worthen, he says are not 

 in a condition to show the structure. 



At the time of writing Dr. Carpenter had evidently not received a 

 package of chippings I had sent him, containing specimens of S. sub- 

 cuspidatus, showing the punctures clearly. He says these examin- 

 ations of the structure of Syringothyris confirm its generic or sub- 

 generic differentiation, established upon other characters, and that the 

 Irish specimen, he believes, belongs to this group. He is still 

 confident, however, that the true S. cuspidatus is not a punctate 

 shell, which you will remember I had not supposed to be the case. 

 I never doubted or questioned the accuracy of Dr. Carpenter's con- 

 clusions on that point, and there is no microscopist living in whose 

 results I have more confidence than in his. 



n. — On the Tertiary Volcanic Eocks of the British Islands, 



By Archibald Geikie, Esq., F.R.S., F.G.S. 



[Abstract from the Proceedings of the Royal Society of Edinburgh, 1866-67, 

 vol. vi. p. 71.] 



THIS paper was in continuation of the series of memoirs on the 

 volcanic rocks of Scotland previously read by the author before 

 the Society,^ and contained the first portion of the results of a survey 

 of the western region, extending from the south of Antrim to the 

 north of Skye. The districts more especially dwelt upon were the 

 islands of Mull, Eigg, and Staffa. After alluding to the writings of 

 previous geologists upon these tracts, more particularly to the dis- 

 covery by the Duke of Argyll of Tertiary leaves under basalt at 

 Ardtun Head, in Mull, the author remarked, that up to this time the 

 great mass of volcanic rocks in the Western Islands has been usually 

 regarded as of Oohtic age — an opinion in which he himself had 

 shared. His object in the present communication was to show that 

 1 See Proceedings, iv. 309, 453, 582, and Transactions, vol, xxii. 633. 



