22 



Tin-: MAMMALIA. 



The Worm-tongukd Edeniaies (\'eniiiliii;^2iia). J)is- 

 tingulshed by the iiossussion of long worm-like 

 tongues, always coaled with an adhesive saliva, 

 which enables them to be used as organs of pre- 

 hension. 



The Ant-eaters. 



The Pangolins. 



THE MARSUPIALS or POUCH-BEARING 

 MAMMALS (Marsiipialia) . 



Non-placental mammals with free digits bearing nails 

 or claws. The young are born in a very imperfect 

 condition, and complete their development attached 

 to teats situated in an external abdominal pou<:h 

 (marsupiuni) supported by two special liones (mar- 

 supial bones) attaclied to the pelvis. The dentition 

 is usually complete but permanent, except in the 

 case of a single premolar, which is shed and 

 renewed. The lower angle of the lower jaw behind 

 is turned inwards. 



The Opo,ssums {Didclphyida). ^Vith five digits on 

 all four feet, and with a very long and strong 

 hallux, which is completely opposable as in 

 monkeys. 

 The Predaceous Marsupials (Rapacia). 



The Perameles Family {PeramcUda). Long eared 

 marsupials with tubercles on the molar teeth, 

 adapting them for crushing insects, the first digit 

 of the fore-feet represented only by a wart or 



tubercle, that of the hind-feet entirely ab.sent, 

 while the second and third digits in the hind- 

 feet are very thin and united together down to 

 tlie claws. 

 The DasvukI'; J''amii,v (JJasyurida). With a more 

 or less wellmarked carnivorous dentition. 



The J'KUTr-EAri.\(; Marsui'IALs {Carpophaga). 



'J'he Phalangek I'amii.y {J'halangistida). With the 

 second and third digits of the hind-feet united, 

 a nailless ojiposable liallux, and well-developed 

 marsupial pouch. 



The }Ieri!Ivokoijs Marsi'I'/ai.s (I'oephaga). Com- 

 posed of forms well adapted for leaping; always 

 with five digits, armed witli strong claws on the 

 short fore-limbs, and very long hinddimbs fitted 

 to bear the whole weight of the body. 



Tnt; Koot-eatino Maksuitals {Rhizupliaga). Com- 

 posed only of a single genus, the wombats 

 (J'hascoluiiiys), with a dentition exactly like that of 

 a rodent, 



THE MONOTREMES (Monolremata). 



Non-placental mammals without true teeth, with the 

 genital and urinary ducts opening along with the 

 rectum into a common chamber (cloaca). They 

 have neither marsupial pouch nor teats, but have 

 nnlk-glands and niarsujjial bones. 



The Ornithokhvnchus. 

 The Echilina. 



NOT \l 



OiN POINTS CONNECTED wmi GEOEOCY KEEP.KRf:]) 'J'O IN TIILS WORK. 



In tlie following pages a section under each 

 order of the Mammals is devoted to the (juestion 

 of the presumed origin or descent of the groiqj, 

 which involves the consideration of its distribution 

 in time. With the view of assisting the reader 

 in following the reasonings in the sections alluded 

 to, a geological table showing the sequence of 

 the rocks forming the crust of the earth is hci-e 

 added. Where subordinate members of the systems 

 given in this table are mentioned in the text, such 

 sub-divisions, for example, as the Keuper or New 

 Red Marl, or local formations, like the Stonesfield 

 Slates, or the Purbeck Beds, an indication is always 

 given of the system to which they belong, so that 



a reference to this tcdjle will enable the reader to 

 understand in a general way the relative order in 

 time of the extinct forms spoken of. 



It may here be mentioned, however, that the 

 order of the strata, as shown in this table, must 

 not be underTtood as giving any indication of the 

 length of time separating forms belonging to differ- 

 ent systems. The thickness of the rocks composing 

 these systems \'aries greatly, and there is presum- 

 ably a corres[)onding variation in the length of 

 time that has elapsed during their formation. Thus, 

 though the first Mammalian remains are found in 

 the Trias, it may be inferred from the thickness of 

 the Ihitish strata, tliat the interval between their 



