Remarks on Ursus labiatus. 207 



relinquish the attack until life is fled; this is an event of 

 rare occurrence, but happens at times when the bear has 

 young ones, as has been before mentioned. 



The Silurian System. By R. I. Murchison, Esq., 

 F.R.S., F.L.S. 



The coal measures at Shrewsbury are described by Mr. 

 Murchison as fringing in the form of a broken, narrow, devi- 

 ous zone ; the promontories of Silurian and Cambrian systems 

 extending from the Breidden hills on the west, to the Wrekin 

 on the east, the base line, or lower edge of which is determined 

 by the headlands and bays of the ancient rocks. Sometimes 

 the carboniferous strata are so completely isolated by these 

 protruding inferior masses, that they consist rather of a 

 number of patches than a continuous band. By this dis- 

 position the coal measures repose unconformably and suc- 

 cessively upon rocks of various ages, from the flanks of 

 which they dip in an opposite direction, and where not 

 obscured by overlying drifted materials, they are seen to 

 graduate upwards into the lower new red sandstone, passing 

 at slight angles of inclination beneath that formation. The 

 principal outcrop of the coal is in a semicircular bay, of 

 which Shrewsbury and Coedway are the eastern and western 

 extremities. Where most developed, this formation contains 

 three seams of coal, which in descending order consist of half 

 yard, yard, and two feet coals ; the quality, thickness, and 

 number of these beds vary in different places, but it may be 

 stated as a general rule, that the lowest, or two feet coal, is 

 the best. " The most remarkable feature of this coal field, 

 and one quite new to geologists when I announced the disco- 

 very, is a band of limestone, varying in thickness from three 

 to eight feet, which lies between the seams of coal." The 

 bed occasionally branches into two, an upper and a lower ; 



1 Continued from p. 50. 



