170 APPENDIX TO REPORT ON OYSTER CULTURE 



originally derived from the decomposition of felspar and slate rocks, and 

 mixed with, more or less, organic matter, most of it being derived from 

 microscopic plants and animals. 



2. Marennes, Department ofCharente. — Specimen of shelly sand [Sable 

 Vazal Coquille) from a locality suitable for breeding, sent by M. Coste. 



Description. — Fine quartzose sand, containing spangles of mica, mixed 

 with a fine bluish highly hydrated mud, which was of a yellow colour 

 when exposed to sunlight. It was full of whole and broken fragments 

 of shells (chiefly Cerithium reticulatum in great abundance, Adeorbis 

 subcarinatus, Buccinum (probably B. undatum). Cardium edule (?), and 

 young oysters). The centre of the mass was very black, and contained 

 Diatomacea, Foraminifera, and Infusoria. Bits of Ulva latissima were 

 also mixed up with this and No. 3 mud from the same locality. The 

 coast of France, in the neighbourhood of Marennes, consists of the 

 chalk marl, or Turonian series of cretaceous rocks, Eocene sandstones 

 and clays, drift gravels, and alluvium. The sand and mud of the shore 

 and littoral sea-bottom is derived chiefly from the tertiary rocks. 



3. Marennes. — Specimen of fine sedimentary mud (Terre Glaise) from a 

 locality which has proved successful both for breeding and fattening, 

 sent by M. Coste. 



Description. — This specimen consisted of the same sand and clay as 

 No. 2, but in different proportions, the clay predominating in this speci- 

 men, the sand in No. 2. Owing to the abundance of clay, the colour 

 was more bluish than that of No. 2, and the centre of the mass much 

 blacker when not exposed to air and light. The intermixed shells were 

 also abundant, but the microscopical organisms were especially abundant. 

 The clay free from shells did not effervesce. 



No trace of copper could be detected in either of the preceding muds 

 from Marennes. 



England. 



4. River Roach, Essex. — Sample of mud from oyster ground. 



Description. — Alluvial mud, consisting of blueish-black slightly cal- 

 careous plastic clay, and much quartzose sand. It was free from pebbles, 

 except some fragments of comminuted shells. The sample examined 

 contained no remains of plants except a pine shaving. The centre of 

 the mass excluded from the air was quite black from the decomposition 

 of organic matter, derived chiefly from microscopical animal organisms, 

 Diatomacea?, &c. No trace of copper was detected in this mud. A 

 copper nail, a pin, or other object of copper ^ or brass, dropped on the 

 shore, or from a boat, may give rise to accidental traces of copper, but 

 otherwise it is not likely that any copper occurs naturally in solution 

 in the water of this river. 



5. River Crouch, Essex. — Sample of mud from oyster ground. 

 Description. — A yellowish gray mixture of quartzose sandy clay, and 



fine gravel, chiefly made up of comminuted bivalve shells, and some 

 pebbles of yellowish and brownish cherty quartz, and chalk flints. The 

 clay separated from the gravel and quartz sand was slightly calcareous. 

 The only remains of plants noticed were bits of Zostera. The fine mud 

 freed from sand like that from the river Roach was highly hydrated, 

 and contained Diatomacese and Infusoria in comparative abundance. 

 The decomposition of these microscopical organisms, and of other vege- 

 table and animal matter, caused the moist mass to blacken when air 

 was excluded. No trace of copper could be detected in this sample also. 



6. Hayling Island, Hampshire. — Sample of mud from Cockle Rythe. 

 Description. — Grayish blue, highly unctuous plastic clay, with inter- 

 mixed fine white sand like that produced by the denudation of certain 



