46 MAMMALIAN DESCENT. [Lect. IL 



finislied labials (lip-cartilages) of tlie types just referee! to. 

 There is, however, just one waif from the Old World, 

 which helps us here. Of the eight hundred known tail- 

 less Amphibia, there are two Toads — one in Surinam, and 

 one in the Cape region — that are tongueless, and these 

 have their Eustachian tubes (or passages between the 

 ear-drum and the throat) opening at the mid-line, as 

 in a bird. 



The Cape Toad (Dactylethra), has nails on his fingers 

 and on his toes, and he is the first of the gill-bearing 

 creatures that has taken on this specialisation — a 

 prophecy of those exquisite supports to the finger-pulps 

 that we see in the daintiest and most elegant of all the 

 Vertebrates. 



Now the children of this first claw-bearer are not like 

 their parents, which themselves are the most modified 

 of all the kindred of the Frog, but are very much like 

 the most bizarre forms of the Ganoid fishes of the Old 

 Eed Sandstone. So much is this the case, that it is 

 difiicult to avoid the conclusion that we have in this 

 larva, whose outline is like that of a half-opened fan, 

 a descendant of one of those old fishes, but a meta- 

 morphosed descendant, only retaining the old family 

 features during the time of its minority.-^ 



Now this larva has a skull which difi'ers from that of 

 the adult Toad, into wdiich it transforms itself, quite as 



1 For the transformation of the skull in the Cape Toad, and for the figures of 

 the larva, see my pax^er in the Philosojjliical Transactions of the Eoyal Society^ 

 1876, plates Ivi.-lix. 



