488 EEroRT— 1893. 



The terminal joints of the great claws of the velvet swimming crab 

 (Portunus puber) and the spider crab {Hyas araneus) were also observed. 



Collections of shells, made by some of the members of the Committee 

 and by the workmen, were submitted to Mr. David Robertson, of Millport, 

 for examination, together with samples of the clay in boxes. His thorough 

 knowledge of the organic remains found in the Scottish shelly clays has 

 been of invaluable service to the Committee, and at their request he has 

 prepared a separate report on the materials which passed through his 

 Lauds. All geologists interested in these researches will cordially appre- 

 ciate the value of his special contributions to this report. 



With the sanction of Sir Archibald Geikie, the Director-General, Mr. 

 James Bennie, of the Geological Survey of Scotland, made a collection of 

 organic remains from the uppermost 6 feet of the shelly clay, the list of 

 shells being determined by Mr. Sharman, palfeontologist to the Geological 

 Survey of England, and revised by Mr. Robertson. 



4. Gravel underlying shelly clay. — This deposit, which was pierced to 

 a depth of 10 feet in the ' main pit,' is of a yellowish brown colour, and of 

 a coarse, unequal quality. The sand in this gravel is coarse-grained, dif- 

 fering from the fine sand above the blue clay and from the sandy matrix 

 of the overlying boulder clay. The deposit is in some parts roughly 

 stratified. The stones vary in size from fine gravel to blocks 6 or 7 

 inches across, while a few measure 14 inches in diameter. The largest 

 block, composed of Old Red Sandstone, measuring 21 inches by 20 inches 

 by 8 inches, occurred from 2 to 3 feet below the bottom of the shelly 

 clay. It was flat-shaped, subangular, and in the pit dipped to the south- 

 west at an angle of about 40° or 45°. 



On referring lo the table of percentage of stones it will be seen that 

 there is a wide difference in the proportion of the blocks of Old Red Sand- 

 stone found in the underlying gravel from that met with in the shelly 

 clay. Indeed the percentage of Old Red blocks in the underlying gravel 

 approaches very nearly to that found in the overlying sandy boulder clay. 

 The blocks of Old Red Sandstone in the gravel were wholly of local 

 origin ; a few wei"e striated, most of them were rough and angular on 

 the edges, and several of the flagstone type were highly decomposed. In 

 like manner the blocks of granite and micaceous gneiss closely resemble 

 similar rocks in situ in the neighbourhood. 



Before closing the ' main pit ' two successful photographs of the section 

 were taken by Mr. Whyte, of Inverness, at the request of the Committee, 

 one at a distance of 40 yards and the other near the edge of the pit (see 

 Plates II. and III.). 



B. — Small Excavation 160 yards S.W. of the 'Main Pit.' 



The Committee made a small excavation on the south bank of the 

 Cassie Burn, 160 yards south-west of the ' main pit,' at the base and west 

 end of the great section of boulder clay already described, which revealed 

 a thin layer of shelly blue clay at a height of 512 feet above the sea- 

 level. The deposit there exposed was only 15 inches thick : it yielded 

 some of the shells found in the ' main pit,' including Astarte, Natica 

 Groenlandica, J.eda pernula, &c., and Foraminifera. 



Here the shelly clay was underlain by 10 inches of hard brown clay, the 

 latter resembling the deposit found on the bank of the Cassie Burn, 233 

 yards south-west of the ' main pit,' to which we may now briefly refer. 



