ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxxix 



characteristic ; thin layers of anthracite and numerous impressions of 

 algae are found in some localities. Seven species of this sandstone 

 are also found in the Silurian system. The authors consider the 

 following deposits to be equivalent to the Spirifer-sandstone of the 

 Rhine : — the sandstone of Meadsfoot lying below the Torquay-lime- 

 stone and containing Pleurodictyon, Sjnrifer macropterus, &c., the 

 sandstones of Couvin and Houffalize in Belgium, those below the 

 limestones of the Eifel, and of Siegen in Westphalia. This is pro- 

 bably equivalent to M. Dumont's Systeme Coblentzien. 



The greater part of Nassau is covered by the Spirifer-sandstone ; 

 the more modern deposits only occur in two districts, in both of which 

 they are associated with various crystalline rocks, and are thrown 

 about in such confusion that nowhere is a consecutive sequence of 

 deposits to be seen, and their relative ages are derived from comparing 

 them with similar beds in less disturbed districts of the Rhenish 

 Provinces. Owing to this circumstance it is impossible to know how 

 many beds may be missing in Nassau ; the authors mention the 

 following, as required to complete the series of formations, viz. — 

 1. The Mountain-limestone, which they suppose to be wanting below 

 the Vosidonomya-slate ; the Ferques-limestone, wdth Spirifer calca- 

 ratus, &c. placed below the mountain-limestone and above the 

 Cypridina-slate ; the Calceola-slates below the Eif el-limestone. 

 With these exceptions, the authors appear to think that the Nassau 

 series contains equivalents of all the deposits found elsewhere 

 between the coal-measures and the Silurian system. 



Upon these conclusions I must remark that I do not concur with 

 the authors in placing their Posidonomya-shales in the coal-measures, 

 and above the mountain-limestone. If we only knew this bed as 

 occurring below the culm-measures in Devonshire and Cornwall, we 

 might hesitate in diifering from two excellent palaeontologists who 

 had devoted so much labour to this subject ; but the position of the 

 Posidonomya-shale admits of no doubt in the county of Northumber- 

 land, where it is to be seen on the coast near Budle, below the lowest 

 part of the mountain-limestone, crowded with the same species ofPosi- 

 donomya as are found in Devon, Cornwall, and Nassau. The true place 

 of this bed is there seen to be at the base of the Carboniferous series. 

 I cannot either agree with these authors in considering the Marwood 

 and Petherwin beds as equivalents of the Cypridina-slates . At p. 5 1 6 

 they quote Cypridina serrato-striata, as found at S. Petherwin, 

 without stating their authority, w'hich, as I believe they never visited 

 Cornwall, has possibly been derived from some mislabelled specimen. 

 I cannot learn that any one has ever found that little Crustacean at 

 Petherwin, or in the corresponding beds of' the Pilton group in North 

 Devon ; but Mr. Godwin- Austen informs me that he saw it, in com- 

 pany with Mr. F. Roemer, in beds which he considers higher in the 

 series. 



On the other hand, nothing is better established than the identity 

 of the Petherwin beds with those of Ferques in the Boulonnais, which 

 are overlaid, as has been shown by Mr. Godwhi-Austen*, by yellow 

 * Journ. Geol. Soc. vol. ix. p. 239. 



