August 24, 1906.] 



SCIENCE. 



249 



through a large part of the deposit, but are 

 very unevenly distributed. In some localities 

 they are present in large numbers and in 

 fairly defined layers. 



The asphalt has in many cases penetrated 

 even the minute pores of the bone, but the 

 original material of the skeleton is practically 

 unchanged. 



The remains recognized up to the present 

 time include the following forms: Elephas, 

 Equus, Bison, a mylodont, Smilodon, Canis 

 indianensis (?), Canis (small species), and 

 camel remains. Numerous bird bones and 

 remains of insects are also found. 



In a considerable number of cases large 

 parts of skeletons are found together, showing 

 that the carcasses were entombed so quickly 

 that there was not sufficient time for decom- 

 position to permit separation of the parts. 



Of the specimens obtained up to the pres- 

 ent tirae an extraordinarily large percentage 

 represent carnivora. The number of car- 

 nivores is certainly relatively larger than the 

 usual percentage in a well-balanced fauna, and 

 this abundance must be attributed to peculiar 

 conditions under which the bones accumulated. 

 Undoubtedly most of the remains are those of 

 animals that have been entrapped or mired 

 in the asphalt at times when it formed a de- 

 posit around tar springs. The surface of the 

 asphalt is very sticky in some places at the 

 present time, and where cuts are opened in it 

 tar may ooze out. Such pools have probably 

 existed here interruptedly through a long 

 period, and particularly during Quaternary 

 time when the deposit was forming. Car- 

 nivores are numerous because they were at- 

 tracted by birds and mammals caught in the 

 asphalt. Perhaps it is not entirely a coin- 

 cidence that the carnivore remains are usually 

 associated with those of birds or mammals, 

 which would be their natural prey. The con- 

 siderable number of young sabre-tooth cats 

 present may indicate that the younger and 

 less experienced individuals were more easily 

 lured into the tar pools. 



During the first examination of the beds 

 several small, pebble-like bones were obtained 

 which resembled the dermal ossicles of the 

 ground-sloth, Grypotherium, recently de- 



scribed by Dr. A. Smith Woodward^ 

 from skin fragTaents obtained in a cave 

 at Last Hope Inlet, Patagonia. The os- 

 sicles were in association with remains of 

 a large ground-sloth somewhat similar to 

 Mylodon in foot structure. Realizing that 

 the peculiar conditions of accumulation of- 

 fered an especially favorable opportunity for 

 preservation of the dermal armor of a ground- 

 sloth, during the second study of the deposits 

 an attempt was made to find a specimen in 

 which the armor might be recognized. Sev- 

 eral hundred yards from the location of the 

 first specimen, a large scapula resembling that 

 of a mylodont was found partly exposed, with 

 a row of small ossicles immediately over the 

 outer side. The section of the bed contain- 

 ing these bones has recently been worked out, 

 and the row of small bones proves to be the 

 edge of a distinct layer including between 250 

 and 300 individuals. They mantle over the 

 outer surface of the scapula, being removed 

 from it by about an inch of asphalt. 



The layer of bones as we find it has prob- 

 ably been disturbed somewhat and does not 

 occupy its original position exactly, but the 

 fact that it remains as a distinct layer with a 

 tendency toward similar orientation of the 

 individual ossicles indicates that the disturb- 

 ance has not been great. As the position of 

 the layer in the asphalt was nearly vertical, 

 the presence of the large number of ossicles 

 together may not be attributed to the washing 

 together of scattered elements on the floor 

 of a small basin of depositioru 



The ossicles are not closely pressed together 

 and are not superimposed. The individuals 

 range in size from a cross-section of 6.5 x 4.5 

 mm. to 21x16 mm. Excepting a few of the 

 largest ones, which are nearly square, the 

 greater number are rounded and rather irreg- 

 ular in form. The outer side is in some cases 

 more regularly modeled than the inner. The 

 surface of the bones is somewhat roughened or 

 pitted in some instances, but no markings are 

 present which would be considered as definite 



^A. Smith Woodward with Dr. F. P. Moreno, 

 Proc. Zool. Soc. Lond., 1899, pp. 144-156, pis. 

 13-15; also A. Smith Woodward, Proc. Zool. Soc. 

 Lond., 1900, pp. 64-79, pis. 5-9. 



