Prof. Morris — Boiling Mollusca in Oolites. 267 



devoted to harrowing descriptions of "divers hurts" received by 

 the congregation. One man, in recording his experiences, stated 

 that he heard " as it. were the hissing of a great shot." It is not 

 improbable that this phenomenon was caused by lightning. 



(To be continued in our next Number.) 



IV. — On the Occuekence of Boring Mollusca in the Oolitic 



Eocks. 1 

 By Prof. J. Morris, F.G.S. 



THE occurrence of perforations due to Lithophagous mollusca has 

 been frequently observed in the Oolitic rocks, viz. in the In- 

 ferior and Great Oolite, Oornbrash, Coral-rag, and Portland beds. 

 During a recent visit, with some of the students of the Agricultural 

 College, Cirencester, to a quarry near there, further evidence of a 

 similar fact was obtained. The quarry is situated near the canal on 

 the farm land of Mr. Sargeant, and has been long worked for road 

 stone and building stone, and, according to the Geological Survey, 

 belongs to the Forest Marble division of the Great Oolite series, and 

 exhibits the structure known as "false-bedding or oblique lamination," 

 and occasionally the flagstones in this and other neighbouring quarries 

 show ripple-marks and tracks of marine animals. 



In looking for fossils, two or three perforated nodules were ob- 

 served on the surface of the ground, and seeing that tbis district is 

 generally free from foreign or transported pebbles, it naturally 

 occurred that they had been exposed and thrown aside and left 

 during the working of the quarry ; upon examination of the 

 section then open, the nodules appeared to occupy the position 

 shown in the following section. A portion of the upper surface has 

 been removed, and the following is a general account of the section 

 seen in the quarry in descending order : — Bubbly limestone, about 

 four feet; brown shaley clay, with thin calcareous shaley bands, 

 slightly oolitic, full of oysters, 0. Soivtrbyi, of different sizes, more 

 or less broken, and other fossils. At the level of this bed in one 

 part of the quarry were the nodules, round or lenticular in shape, of a 

 fine, compact, highly calcareous and ferruginous claystone, or indurated 

 marl, of light brown colour, both the under, lateral and upper sur- 

 faces of which have been perforated by some boring mollusc, as 

 Lithodomus or Gastrochcena ; the holes are pear-shaped, and are 

 found all round the margin of the nodules, and are filled either with 

 a yellowish brown mud with some oolite grains, due to subsequent 

 infiltration, or with crystallized calcite ; in some cases the shells of 

 the mollusc have been preserved. Besides the perforations, the 

 surfaces of many of the nodules are covered with attached valves of 

 oysters and a carinated Serpula, the interspaces, as well as the valves 

 of the oysters, being incrusted with a delicate species belonging to 

 the Polyzoa, probably a Berenicea or Diastopora ; the thickness of 

 this bed is about three feet. The nodules are coated with similar 



1 Abstracted and revised by tie author from the Agricultural Students Gazette, 

 April, 1875. 



