150 DREDGINGS OF THE MARINE BIOLOGICAL ASSOCIATION : 



mixture, with mottling of rich orange -brown, less granular, substance, 

 and grains and short irregular lines of an almost opaque dark brown. 

 No undoubted organic remains. 



M. 53b. 



A light brown rock, a harder variety of the preceding, contains 

 calcite veins, and one joint-face shows well-developed crystals. The 

 laminae of tliis rock are alternately of closer and of more open 

 texture. 



The section is made in one of the harder layers and corresponds 

 with 53a, except that it is lighter in general shade and the orange- 

 brown portions are much less in proportion to the whole. 



M. 53c. 



Drab-coloured compact rock in slabs, one face of which is usually 

 obviously a joint surface recently broken, and one face much bored, 

 probably by annelids. The section shows a pale brown rock wholly 

 but minvitely granular, almost entirely calcite, with an occasional 

 narrow vein of clear calcite, and small scattered brown and black 

 granules. No trace of organisms. This forms the last of a series of 

 which 53a and 53b are the first members. 



M. 56a. S. 25° W. Edd., 343 miles. 



A dull brown limestone of light shade. 



Contains numerous fragments of shells and rather frequent echino- 

 derm spines, but no foraininifera. 



M. 44. S. 17° W. Edd., 29 8 miles. 



Buff limestone, apparently liassic. 



CRETACEOUS. 

 CHALK. 



A very hard, yellow, or cream-coloured, chalk is of frequent oc- 

 currence ; generally the exterior of the pebble is brown, and this colour 

 extends some slight depth into the stone, getting less in intensity 

 until it fades into the yellow or cream-colour. Unless the stone 

 happens to be much bored it usually requires a considerable blow to 

 break it. 



M. 26a. S. 20° W. Edd., 18 4 miles. 



Hard, cream-coloured chalk. Minutely granular texture. Crowded 

 with small organisms. Many good sections of small foraminifera. 

 Fragments of larger shells frequent. Some of the foraminifera in- 

 filled with a yellow-orange substance. Several textularia. Fragments 

 of nodosaria, and some rotaline forms and s'lobif^erina. 



