490 MR. A. H. G. DORAN ON THE MORPHOLOGY 



aspect above the scale-like process from the head of the malleus, which covers the 

 body. The processus longus is not much longer than the short crus ; it is straight and 

 flattened, and wholly concealed from without by the malleus, except its extremity, which 

 is bent inwards, and bears a very small but distinct Sylvian apophysis. 



It will be seen at a glance that the kind of ankylosis between the two outer ossi- 

 cula in Echidna is totally different from their mode of union in Porcupines and Cavies, 

 where the malleus and incus are joined on the same level externally as internally ; 

 and, besides, there is always in the latter animals a peculiar development of the head 

 of the malleus forwards, away from the incus, instead of the scale-like prolongation of 

 the head on to the outer side of the latter ossicle. 



The incus of Echidna is, after all, not so very much smaller in proportion to the 

 malleus than in many Marsupials ; only it is more flattened ; flatness is also seen in the 

 same ossicle in those Rodents where it is fused with the malleus. I have never found 

 it to be so loosely attached to the malleus as in young skulls of the Duck-bill. 



The stapes is absolutely columelliform. Its head is very small, with no trace of any 

 tubercle for the stapedius-tendon, which does not appear to exist in this animal *. The 

 column bears not a trace of any subdivision into crura ; it is rather long, and the foot- 

 plate is almost perfectly circular. 



What relation does the stapes of this avowedly low mammal bear to the columelliform 

 representative of the same in higher animals on one hand and in the Sauropsida on the 

 other ? Is the column of the stapes of Echidna formed of the same element or elements 

 as in Aves ? 



By referring to the description of the stapes in the Marsupialia, it will be seen that 

 this bone is of the same perfectly columelliform type in the Dasyures, Wombats, Bandi- 

 coots, and most Phalangers, as in the Echidna ; and among the Edentata, Ifanis has a 

 similar type of stapes. In some of the above animals the base of the ossicle in question 

 is less perfectly circular than in Echidna, and hence more like the foot-plate of th^ 

 bicrurate stapes of Homo. Then the column is shorter in some of these animals than in 

 the Porcupine Ant-eater. 



But it happens that all the above characters rather strengthen the alliance between 

 Marsupials, the Manidge, and the Monotremata, than show that those animals are parti- 

 cularly ornithic or reptilian. 



In some birds where the column is almost as short as in these mammals, it divides 

 distinctly into two crura, as distinctly as in Macropus and Tolypeutes. This is the 

 case with the Nightingale (PI. LXIV. fig. 45) and Redstart ; or at least it is so in the 

 specimens in the College collection. In others, where the column is very long, it may 

 also divide into two crura near the foot-plate, as is very clear in the Eagle (Aquila, 

 PI. LXIV. fig. 46). Besides, the foot-plate in many Pinches and other birds, and in 

 Crocodiles and other reptiles, is not of the circular outline seen in the Echidna, but as 

 long horizontally, and narrow vertically, as in the stapes of the highest mammals. 



Then, without plunging into unsettled questions of development, does the column of 



* Huxley. I have never seen a vestige of an}- representative of that muscle. 



