54 Professor T. Bupert Jones — History of Sarsens. 



'glabella,' like those that have been attributed to impressions of 

 the limuloid limbs. 



The ' pleuree ' (if we may use the nomenclature adopted in th© 

 case of trilobites, with which these forms provide so valuable a link) 

 are furrowed, while in Heniiaspis (Limuloides) they are unfurrowed. 

 Traces of three segments are preserved in the more perfect specimen. 

 Even the somewhat abrupt posterior bend, so characteristic of the 

 pleurae of Helinurus reginoi, is noticeable in the first segment of 

 Belinnrus Jciltorlcensis, and was doubtless repeated in the others. 



Frotolimulus (Prestwichia) erieusis, described from the Devonian 

 of Pennsylvania by H. S. Williams and A. S. Packard,^ is only 

 known by its under surface ; but the cephalic shield does not 

 resemble that of the Kiltorkan specimens. 



I feel, then, that Belinurus may safely be regarded as occurring 

 in the Upper Old Ked Sandstone of Ireland, which some authors have 

 proposed to include in the Lower Carboniferous Series. There seems- 

 no reason to depart from the determination made by Mr. Baily and 

 Dr. Woodward thirty years ago, a determination that has become 

 widely known through the works of Zittel and other paleontologists. 



III. — History of the Sarsens. 



By Professor T. Rupert Jones, F.R.S., F.G.S., etc. 



Additional Notes. — These further references and fuller quotations 

 are here given with the view of making the History of the Sarsens, 

 or Sarsen Stones, more complete and more easily available, 

 especially by indicating the chronological succession of observed- 

 facts and published opinions. 



§ 1. Origin and Constitution of the Stones called ' Sarsens.' 



§ 2. Fossils in Sarsens. 



I 3. Localities. I. In the Counties north of the Thames : (1) Northamptonshirep. 

 (2) Suffolk, (3) Essex, (4) Hertfordshire, (5) Buckinghamshire, (6) Oxford- 

 shire, (7) Middlesex. II. In the Counties south of the Thames : (8) Kent, 

 (9) Surrey, (10) Hampshire, (U) Berkshire, (12) Wiltshire, (13) Dorset. 

 (14) Somerset, (15) Devon. 



§ 4. Bibliographic List. 



§ 1. Origin and Constitution of Saksens. 



(See also Part i in Wilts Mag., 1886, p. 126.) 



1819. G. B. Greenough, in his " Critical Examination of the 

 First Principles of Geology," p. 112, says that the Grey weather 

 Stones (' Grey wether sandstone,' etc., p. 293), scattered over the 

 southern counties of England, have been evidently derived frona 

 the destruction of a rock which once lay over the Chalk. 



1871. In the Transactions of the Newbury District Field Club, 

 vol. i, p. 99, Sarsens are referred to as "indurated blocks of sand- 

 stones and conglomerates." 



1882 and 1885. Sir Archibald Geikie, treating of siliceous 

 cements in sandstones, writes, "where the component particles are 



^ Packard, " Carboniferous Xiphosurous Fauna of JYorth America": Mem. Nat.. 

 Acad. Sci. Washington, vol. iii (1886), p. 150. 



i 



