IN THE UNITED KINGDOM AND FRANCE. 49 



ficient quantity of highly hydrated clay to render the sand adhe- 

 sive and to preserve it from becoming a mere loose running mass. 

 In the clayey grounds there must always be calcareous mud to 

 make the clay porous and prevent it becoming too hard — clay 

 marls with some intermixed sand being perhaps the best of all 

 materials for oyster grounds. 



Professor Sullivan also furnishes most valuable information as 

 to the places on the seaboard where the bottom is composed of 

 earth of an analogous character to that where oysters exist natu- 

 rally, or where artificial cultivation lias succeeded. He also gives 

 an analysis of the earth in some places where failures have oc- 

 curred. 



The earth known as the London clay appears to be the soil pe- 

 culiarly adapted for oysters. It may be well here to explain that 

 the term " London clay" is employed in a general and in a special 

 sense. In the former it is used as a collective name for a number 

 of beds of the older tertiary formation, consisting of gravels and 

 sands below and of clays above, occupying a large portion of Sus- 

 sex, Essex, and Middlesex, and portions of Berks, Surrey, and 

 Kent. In the special or more limited sense it is applied to the 

 blueish or blackish clay, sometimes mixed with a greenish-coloured 

 earth and white sand, which forms the upper parts of the beds 

 just mentioned. London clay is plastic clay, not differing much in 

 chemical composition from ordinary potters' clay. It is sometimes 

 highly calcareous, so as to pass it into a marly clay, and, as at 

 Harwich, into a regular calcareous rock. The river and shore 

 muds formed from the London clay are, however, largely mingled 

 with sand derived from the lower beds above mentioned and from 

 the overlying sandy beds such as the silicious sands of Bagshot in 

 Surrey and New Forest in Hampshire, &c. All fruitful oyster 

 muds contain organic matter, always due in part to the presence 

 of infusorise, and sometimes in part to small alga? or confervae, re- 

 mains of shell-fish and other marine creatures. 



It will be seen in the report that this London clay is to be found 

 in many places in the rivers and around the shores of Ireland. 



We are, therefore, enabled to state that, both as regards tem- 

 perature and soil, Ireland appears to be capable of a far greater 

 amount of oyster production than is yielded at present. 



There are, however, other conditions to be fulfilled the exist- 

 ence of which can only be ascertained by observation and expe- 

 rience. 



We deem it incumbent on us to recommend the utmost caution 

 with respect to all attempts at artificial cultivation, particularly 

 as regards propagation. We have found fully ten instances of 

 success in fattening for the one in the w T ay of production. Ex- 

 periments in the former are much more conveniently and inexpen- 

 sively made than in the latter, more especially where the tank or 

 enclosure system is attempted. 



Before, therefore, enterprises of the latter kind are undertaken 

 it should be carefully considered whether all the requirements 

 which experience has pointed to as essential to success would be 

 likely to be fulfilled, not the least important of which would be 



