chap. xi. Mammiferous Remains at S. Julian. 347 



plain is certain ; and that this gravel, at the height of 

 ninety feet, was spread out long after the existence of 

 recent shells, is scarcely less certain. For, it was 

 shown in the eighth chapter, that this line of coast has 

 been upheaved with remarkable equability, and that 

 over a vast space both north and south of S. Julian, 

 recent species of shells are strewed on (or embedded in) 

 the surface of the 250 feet plain, and of the 350 feet 

 plain up to a height of 400 feet. These wide step- 

 formed plains have been formed by the denuding action 

 of the coast-waves on the old tertiary strata ; and 

 therefore, when the surface of the 350 feet plain, with 

 the shells on it, first rose above the level of the sea, 

 the 250 feet plain did not exist, and its formation, as 

 well as the spreading out of the gravel on its summit, 

 must have taken place subsequently. So also the 

 denudation and the gravel-covering of the ninety feet 

 plain must have taken place subsequently to the eleva- 

 tion of the 250 feet plain, on which recent shells are 

 also strewed. Hence there cannot be any doubt that 

 the Macranchenia, which certainly was entombed in a 

 fresh state, and which must have been alive after the 

 spreading out of the gravel on the ninety feet plain, 

 existed, not only subsequently to the upraised shells on 

 the surface of the 250 feet plain, but also to those on 

 the 350 to 400 feet plain : these shells, eight in number 

 (namely, three species of Mytilus, two of Patella, one 

 Fusus, Voluta, and Balanus), are undoubtedly recent 

 species, and are the commonest kinds now living on 

 this coast. At Punta Alta in B. Blanca, I remarked 

 how marvellous it was, that the Toxodon, a mammifer 

 so unlike to all known genera, should have co-existed 

 with twenty-three still living marine animals ; and now 

 we find that the Macrauchenia, a quadruped only a 

 little less anomalous than the Toxodon, also co-existed 



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