88 EXPLANATIONS. 



the marsujoials, which are of course unequivocally 

 land animals. I have only here to refer to the 

 fourth edition of my book,— published two months 

 before the appearance of the review, and while I 

 was unrecking of any great objection being 

 grounded on this point — where it is suggested 

 that the peculiar organization of the marsupials 

 points to their having been derived through a 

 different medium from other mammals. The 

 critic, eager to let nothing escape, tells us that 

 there are other land mammals lower in organic 

 type than the marsupials. One answer to this 

 objection might be found in an explanation of 

 my views respecting the ornithic descent of these 

 animals ; but I am unwilling to pause upon such 

 an inferior matter, and will therefore meet him 

 with the question, if any other mammals show 

 that lowly grade of organization which is marked 

 by the absence of a placenta } " There are no 

 other organic types," he says, " to which they [the 

 marsupials] offer the shadow of a near affinity. 

 They are therefore in direct antagonism with the 

 scheme of regular development." To this it may 



Oolite of Enstone, near Woodstock, Oxon, which was examined 

 by Cuvier and pronounced to be cetaceous ,- and also a portion of a 

 very large rib, apparently of a whale, from the same locality." 

 Buckland's Bridgtwater Treatise, I. 115, note. 



