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Show 252 EOCENE PERIOD. [Ch. xvnr. which frequently float on the surface of rivers together with wood. h · 1 M. Prevost h as, tl)erefore ' suOo 'gested t at a r1ver m. ay 1. ave swept away t 11 e b 0 d1'e s of animal.s ' a.n d the plants wluch hvcd on I· ts b orel et.s , or in the lakes wluch 1t traverse. d, and .m ay have carn·e d t 1I em d ow 11 into the centre of the g.u lf mto winch flowed 1 tcrs imprem1ated with sulphate of hme. W c know that t 1e wa b 1 d · 1 · the Fiume Salso in Sicily enters the sea ~o c 1ar?e wlt 1 vanous salts that the thirsty cattle refuse to drmk of ~t. A stream of 1 1 t r as white as milk, descends mto the sea from SU p lUreOUS wa e ' t 11 e vo1 c am·e m ou11tain of Idienne, on. the east of. Jav. a ; and a great b o d y o f llot water' charged w.1 th sulph.u ric ac1dJ rushed d own f rom t1 1e Same on one occaswn, .a nd mundat. ed a large tract of coun t ry, destruvJ inOo' ' by its nox1ous .p r.o perties, , a.l l the vegeta t1. 011 * . In like manner the Pusamb10J or Vmegar n·v er ' of c o1 o m b1'a, which rises at the foot of Purac. e, an ex- tm· ct vo1 c ano 7500 feet above the lev.e l . of t.h e sea, 1s .s trong.l y 1· mpregna t ed wi th sulpl1Uric and munat1c ac1d, and with oxide of iron. We may easily suppose the waters of such streams to have properties noxious to marine animals, ~nd in th.is n~anner we may expl al'n the entire absence of marme remams 111 the ossi:fferous gypsum t · . There are no pebbles or coarse sand in the g~psum, a cir-cums t ance wl l.lch aOo 'rees well with the hypothesis that . thes.e b d were precipitated from water holding sulphate of hme m e s ~r · 1 Tl so 1u t1. 0nJ an d floatinOo' the remains of diuerent amma s.. 1C bones of land quadrupeds however are not confined entirely !o the fresh-water formation to which the gypsum belongs, for the remains of a Palreotherium, together with some fr.csh-watcr shells have been found in a marine stratum belongmg to the calcaire O'rossier at Beauchamp. . In th: O"ypsum the remains of about fifty species of ~ua-drupeds l:ave been found all extinct and nearly four-fifths "' Leyd e Magaz. voor vVctensch Konst en Lett., parb.e v. ca 1u'e r · 71 Cited I. P· . by Rozet, Journ. de Geologie, tum. i. P· 43. , t M. c. Prevost, Submert~ions l!crativcs, &c. Note 23• Ch.XVIII.J PARIS DASIN-GYPSUM. 253 of them belonging to a division of the order Pachydermata, which is now only represented by four living species, namely by three tapirs and the daman of the Cape. A few carni- . vorous animals are associated) among which are a species of fox and gennet. Of the Rodentia) a dormouse and a squirrel; of the InsectivoraJ a bat; and of the Marsupialia, (an order now confined to America, Australia) and some contiguous islands,) an opossum, have been discovered. Of birds about ten species have been ascertained, the skeletons of some of which are entire. None of them are rcferriblc to existing species *. The same remark applies to the fish, according to MM. Cuvicr and Agassiz, as also to the reptiles. Among the last are crocodiles and tortoises of the genera Emys and Trionix. The tribe of land quadrupeds most abundant in this formation is such as now inhabits alluvial plains and marshes and the banks of rivers and lakes, a class most exposed to suffer by river inundations. Whether the disproportion of carnivorous animals can be ascribed to this cause, or whether they were comparatively small in number and dimensions, as in the indi- · genous fauna of Australia, when first known to Europeans, is a point on which it would be rash perhaps to offer an opinion in the present state of our knowledge. '\V e have no reason to be surprised that all the species of vertebrated animals hitherto observed are extinct, when we recollect that out of 1122 species of fossil testacea obtained from the Paris basin, 38 only can be identified with species now living. W c have more than once adverted to the fact that extinct mammalia are often found associated with assemblages of recent shells, a fact from which we have inferred the inferior duration of species in mammnlia as compared to the testacea; and it is not improbable that the higher order of animals in general may more readily become extinct than the marine molluscs. Some of the thirty-eight species of testacea above alluded to as havinO' • ' b survived from the Eocene period to our own times, have now a * Cuvier, Oss. Foss. tom. iii. p. 255. |