METHODS — PAL^ONTOLOGICAL 35 



marsupials and birds which have apparently died where they 

 lie, literally, in hundreds. The facts that the bones of in- 

 dividuals are often unbroken, close together, and, frequently, 

 in their proper relative positions, the attitude of many of 

 the bodies and the character of the matrix in which they are 

 embedded, negative any theory that they have been carried 

 thither by floods. The probability is, rather, that they met 

 their deaths by being entombed in the effort to reach food or 

 water, just as even now happens in dry seasons, to hundreds 

 of cattle which, exhausted by thirst and starvation, are unable 

 to extricate themselves from the boggy places that they have 

 entered in pursuit either of water or of the little green herbage 

 due to its presence. The accumulation of so many bodies 

 in one locaUty points to the fact of their assemblage around 

 one of the last remaining oases in the region of desiccation 

 which succeeded an antecedent condition of plenteous rains 

 and abundant waters." 



It is a very general experience in collecting fossil mammals 

 to find that they are not evenly or uniformly distributed 

 through the beds, but rather occur in "pockets," where great 

 numbers of individuals are crowded together, while between 

 the "pockets" are long stretches of barren ground. It is 

 equally common to find the bones thickly distributed in cer- 

 tain layers, or beds, and the layers above and below entirely 

 wanting in fossils. The reasons for this mode of occurrence 

 have been partially explained in the foregoing paragraphs, 

 but the reason differs for each particular mode of entombment. 

 The important part played by drought in causing such ac- 

 cumulation of closely crowded bodies in swamps and mud- 

 holes is indicated in the quotations from Darwin and Stirling ; 

 but similar accumulations may take place on hard ground, 

 as was observed in central Africa by Gregory. "Here and 

 there around a water hole we found acres of ground white 

 with the bones of rhinoceroses and zebra, gazelle and ante- 

 lope, jackal and hyena. . . . These animals had crowded 



