And now one of the richest known accumulations of fossil mammals belongs to the middle of the secondary series; and true mammals have been discovered in the new red sandstone at nearly the commencement of this great series.

现在， 已知最丰富的哺乳动物化石群之一属于第二系列的中部；在这个伟大系列的开始阶段， 在新的红砂岩中发现了真正的哺乳动物。