Vol. 67.] THE AVONIAN OF BURRINGTON COMBE. 345 



described by one of us. 1 The 'china-stones'* of the Burrington 

 section agree with those of the Avon section in their extremely 

 compact horny texture and conchoidal fracture, but are not so 

 black on a freshly-broken surface, and do not weather so white as 

 do those from S x in the Avon section. 



The ' concretionary beds,' which are best seen at about the middle 

 of the quarry, are essentially the same as those of the Avon section, 

 and the account given in the paper already referred to of the 

 peculiar ' Landscape ' or ' Cotham-Marble ? structure is applicable to 

 the Burrington rocks. Sections (see PI. XXVIII, fig. 1) show that 

 this type of rock is to a large extent made up of a mass of small 

 interlacing tubules, which Dr. Bather suggests may be calcareous 

 algae. Dr. G. J. Hinde has kindly examined two slides containing 

 these bodies, and writes as follows : — 



' They have the appearance, as y u say, of intertwining tubules, but 1 do 

 not detect any definite walls to the tubes, if they are such. Still, it is quite 

 possible that they might be tubules or canals in which the walls have disap- 

 peared. They remind me strongly of the structure of the peculiar bodies 

 from the Carboniferous Limestone of Belgium, described by Prof. Griirich, of 

 Breslau, under the name of Spongiostroma. 2 Gurich places his forms as 

 protozoans, but cannot indicate any particular group of Protozoa as nearly 

 related. Prof. Rothpletz describes somewhat similar bodies from the Silurian 

 of Gotland and from (Esel, and he considers them as hydrozoa.' 3 



At several points the limestone of S 2 shows brecciation. In 

 Quarry 1 a distinct type occurs, consisting of fragments of horny or 

 more or less oolitic limestone Avhich reach a length of an inch and 

 a half, and are united by rather coarsely crystalline calcite. At 

 other levels the brecciation is on too small a scale to be visible in a 

 hand-specimen. In the oolitic limestone from the upper part of 

 S„ the grains tend to be relatively large and somewhat scattered : 

 the centre round which a grain has formed is frequently a foraminifer 

 (see PI. XXVIII, fig. 2). Sometimes the concretionary coating of 

 calcium carbonate is developed round a Seminula in the way de- 

 scribed by one of us, in the case of the ' brecciated pisolite ' of the 

 Avon section. 



S., (c). These rocks occupy the northern third of the hillside be- 

 tween Quarries 1 and 2. Their base is taken as being marked by the 

 highest chert-band. They are in the main foraminiferal limestones 

 with bands of Seminula, but are sometimes oolitic and include, 

 especially in the upper part, very fine-grained, compact, horny 

 limestone (41) * of china-stone type, but differing from the more 



1 Proc. Bristol Nat. Soc. ser. 4, vol. i (1906-1907) pp. 87-100. 



2 See ' Les Spongiostromides clu Viseen de la Province de Namur ' Mem. 

 Mus. Boy. Hist. Nat. Belg. vol. iii (1906) pp. 1-55 & pis. i-xxiii; also Neues 

 Jahrb. vol. i (1907) pp. 131-38 & pi. ix. 



3 See K. Svenska Vetensk.-Akad. Handl. n s. vol. xliii (1903) No. 5, 

 pp. 17-20 & pis. v-vi. 



4 The numerals in parentheses refer to particular spots shown in figs. 3-10 

 .{pp. 354-61) at which important rock-types were obtained. 



Q. J. G. S. No. 267. 2 b 



