326 Proceedings of the British Association. 



had furnished him additional proof of the correctness of the ar- 

 rangement of these rocks, which he had proposed in a paper read 

 at the Glasgow meeting. 



A report was read from the committee appointed at Glasgow, 

 for obtaining instruments and registers to record shocks of earth- 

 quakes in Scotland and Ireland. Two instruments were devised 

 and set up for this purpose, about January 1, 1841, near Comrie, 

 in Scotland, viz. the common Pendulum Seismometer, and the 

 inverted Pendulum Seismometer. No very important results had 

 hitherto been obtained, and it is now proposed to adopt new in- 

 struments of greater scope and sensitiveness than those before 

 employed. 



On the occurrence of some minute Fossil Crustaceans in Pa- 

 laeozoic Rocks, by Mr. John Phillips. — After mentioning various 

 places in which these animals have been found, he states that he 

 had lately observed in Pembrokeshire, in the lowest shales of the 

 mountain limestone, within ten feet of the old red sandstone, 

 beds of Cyprides very similar to those in the black shales of the 

 •upper coal measures in Manchester. These are probably the most 

 ancient specimens of the group yet discovered. The circumstan- 

 ces under which these Crustaceans are found at the present day, 

 appear to aigree with those attending their occurrence in a fossil 

 state ; the recent Cyprides seem destined to consume the perishing 

 parts of animal and vegetable substances, and the fossil species 

 are generally associated with portions of fishes near Manchester, 

 and elsewhere. Probably these remains occur under many cir- 

 cumstances, but to ascertain all the conditions under which they 

 lived, requires attention to many sorts of strata not often sus- 

 pected to contain remains. Very remarkable conditions occurred 

 when the old red sandstone ceased to be deposited : for then, after 

 a long series of formations, with no trace of organic remains, we 

 find in the beds immediately above, thousands of minute Crusta- 

 ceans, bone beds, layers of Brachiopoda, &c. of marine origin; 

 and encouraged by this example, we may expect to find them in 

 beds of still higher antiquity. 



A paper was read by Mr. W. Walker, on the Geological Chan- 

 ges produced by the Saxicava rugosa in Plymouth Sound. — The 

 ^S*. rugosa appears to be the prevailing perforator of the limestone 

 rocks, and it is the author's opinion that these operations have 

 been carried on during such long periods as to destroy rocks, and 

 make deep water where shoals previously existed. 



