and its Significance in Systematic Zoology, 85 



Gould) ; and the true Kangaroos (Macropus) are equally nearly 

 approached in form by the Cape Leaping Hare (Pcdctes capensis, 

 111.). There is also a considerable resemblance between the 

 Wombat or Badger of the Australian colonists (Phascolomys 

 Wombat, Per. and Les.) and the Rodent Cavies and Lagomys ; 

 while a further homomorphism occurs between individuals be- 

 longing to aberrant groups in either Order, viz. the Brazilian 

 Porcupine (Synetheres) among the Rodents, and the Echidna 

 among the Monotremes, whose relation to the Insectivora has 

 already been pointed out. 



These external resemblances between Rodents and Marsupials 

 are none the less remarkable when we learn that there i§ less true 

 affinity between them than between the Marsupials and most 

 other Orders ; for Mr. Waterhouse, in his excellent l History of 

 the Marsupialia/ remarks that in them "we find representatives 

 of most of the other Orders of Mammalia. The Quadrumana 

 are represented by the Phalangcrs ; the Carnivora by the Da- 

 syuri; the Insectivora by the small Phaseogales; the Rumi- 

 nantia by the Kangaroos, and the Edentata by the Monotremes." 

 He adds : " The Cheiroptera arc not represented by any known 

 Marsupial animals, and the Rodents are represented by a single 

 species only" — the species referred to being the Wombat. 



Lastly, the Marsupialia, besides their homomorphism with 

 the Rodents, have, through the Ursine Opossum, or Native 

 Devil of Van Diemen's Land (Dasyurus), a singular relation- 

 ship to the Carnivorous genus Ursus, as well as, through the 

 Squirrel Petaurus, to the Bats. 



Space will not permit me to compare the forms of Inverte- 

 brata one with another. Among them many remarkable analo- 

 gies of form may be observed; and even between the Vertebrate 

 and Invertebrata they will be found to occur. Further illustra- 

 tions of this subject may be found in a paper by the author in 

 the ' Proceedings ' of the Liverpool Literary and Philosophical 

 Society for the p'ast session. 



On no principle of gradation oiform can these resemblances, 

 unaccompanied as they are by homologous relations, be accounted 

 for. Some are advances, others degradations of form ; and we 

 must look for some deeper and more subtle cause which shall 

 connect animals so widely separated as are the members of 

 distinct subkingdoms. There is one circumstance, however, 

 which cannot fail to strike the thoughtful inquirer, and which, 

 I think, holds out a clue to the remarkable facts to which I 

 have just now briefly alluded. The circumstance to which I 

 refer is, that, in not a few cases, striking deviations from typical 

 form are accompanied by no less striking modifications of typi- 

 cal habits ; and further, that these modified habits have a strong 



