98 



tracted towards the neck ; these masses are always surrounded by athin 

 nacreous case, brilliant as the most vivid Lumachella ; the nacre seems 

 to have formed the lining of a fibrous thin shelly substance, which 

 together with this nacreous lining was prolonged into a hollow cone 

 like that of a belemnite, beyond the neck of the ink-bag ; close to 

 the base of the ink-bag there is a series of circular transverse plates 

 and narrow chambers, resembling the chambered alveolus within the 

 cone of a belemnite ; but beyond the apex of this alveolus, no spa- 

 those body has been found. 



The author infers, that the animal from which these fossil ink-bags 

 are derived, was some unknown cephalopode, nearly allied in its in- 

 ternal structure to the inhabitant of the belemnite 5 the circular form 

 of the septa showing that they cannot be referred to the molluscous 

 inhabitant of any nautilus or Cornu-ammonis. 



Feb. 6th. — A paper was read " On the Oolitic District of Bath," 

 by William Lonsdale, Esq., of Bath-Easton. 



The tract described in this paper comprehends a space included 

 between lines passing,' — on the north, from Wicke north-west of 

 Bath, through Marshfield, Kingston-St. Michael, and Lynham, to the 

 Chalk-downs north of Calne and Cherhillj and on the south and 

 south-east, — from the south of Radstock, through Frome andWestbuiy 

 to Devizes. The author refers to the works of Mr. Smith, and of 

 Messrs. Conybeare, De la Beche, and Phillips, as the principal pub- 

 lished authorities on the district ; and states his obligations for much 

 valuable information to the Rev. B. Richardson of Farleigh, near Bath. 



The geological boundaries of this tract are, on the west and north- 

 west, the lias 5 on the south-east and east, the Chalk-downs, extend- 

 ing from Salisbury Plain near Westbury to near Urchford, and thence 

 to Cherhill-hill on the east of Calne. The series of strata which it 

 includes, being the following, in a descending order. — 



Strata. Thickness. Strata. lliickness. 



Feet. Feet. 



Lower chalk Forest marble (continued) 



Chalk marl 150 clay 10 



Upper green-sand 75 coarse oolite 25 



Gault 150 sandy clay and grit 10 



Lower green-sand 50 Bradford-clay .... 50 



Kimmeridge-clay. . . 150? Great Oolite 140 



Upper calcareous grit 10 Fuller's-earth .... 150 



Coral rag 40 Inferior Oolite 



clay 40 sandy oolite 60 



calcareous grit .... 50 sand and grit 70 



Oxford clay 300? — 130 



Kelloway rock 5 marlstone . . .- 10 



Cornbrash 16 Lias ; upper marl 200 



Forest marble . blue lias 50 



clay 15 white lias 10, 



sand and grit .... 40 lower marl. ... 20 



■ 280? 



The surface of the country described in this paper is characterized 



