Manchester Memoirs, Vol. xlii. ( 1 898), No. 4. 5 



'^ P lacuna placenta, which seems to be common both on 

 the Mekran Coast and in the Persian Gulf, is preserved at 

 Karachi and in the neighbourhood, and is a source of 

 revenue to the Indian Government, the right to collect 

 them for the pearls they may contain being sold every few- 

 years. No edible bivalves are collected at Karachi for the 

 market, as at Bombay. 



" West of Karachi, almost all the species given in the 

 list have been dredged in depths varying from 5 to 60 

 fathoms, soft mud, muddy sand, and hard clayey mud 

 being the kind of bottom usually met with. A few 

 isolated patches of soft muddy sand, with loose stones, 

 liave been found at a depth of about 7 fathoms, and these 

 are always profitable to dredge over — whilst, on the other 

 hand, the hard clayey mud is not only utterly unprofitable 

 as regards living specimens, but is very troublesome in 

 choking the dredge. 



"The chief features of the Mekran Coast vary very 

 little — high, rugged hills, both in the fore and back 

 ground, with occasional valleys, the whole presenting as 

 barren and desolate an appearance as it is possible to 

 imagine. The whole of this coast has undoubtedly formed 

 part of the sea bottom at some prehistoric age, as the 

 highest hills are covered with a layer of hard stony 

 substance, which has originally been mud, and in which are 

 found quantities of shells in a more or less fossilized state. 

 On the Gwadur Headland, 480 feet above sea level, large 

 specimens of Eburna Molliana in an almost perfect state 

 have been found, the colouring in one instance being almost 

 as fresh as that of a living specimen. Large numbers of 

 single valves of Pecten Townsendi have also been found in 

 the same place in an equally good condition, in fact the 

 whole of the Mekran Coast and Persian Gulf offers a 

 rich field to geologists. Several of the rocky reefs 

 between high and low watermark, and the long stretches 



