April 21, 1882.] 



♦ KNOWLEDGE • 



533 



but two distinct bones. One of these is the shoulder-Made, 

 OTScapiila, the other beingthe collar-bone, or c7n nVA'. In the 

 shoulder of a bird (Fig. 3) there are three distinct elements, 

 the scajjiihj (Fig. 3, d) clavicle (c), and the coracoid bone 

 (b,L ) This last in quadrupeds, a mere process of the shoulder- 

 blade, forms, as shown in Figure 3, the chief support of the 

 wing in birds, and arises directly from the breastbone (a). 

 Now, it is a remarkable fact that the Ornithorhynchus and 

 Ecliidna, alone of all quadrupeds, possess a distinct coracoid 

 /■one, which, as in birds and reptiles, springs from the breast- 

 lione. Again, there is another bone, called the epicoracoid, 

 which is found in reptiles, and which exists likewise in the 



Fig. 3. — Shonklcr-bones of (A) an Eagle, and (B) an Ostrich. 



Ornithorhynchus and Echidna. In the bird, again, as every- 

 body knows, the two collar-bones unite to form the " merry- 

 thought," or fiircuhtm (Fig. 3, c). In these lowest quad- 

 rupeds the collar-bones (Fig. 4, cc) are joined by a T- 

 shaped bone, called the interclavicle (Fig. 4, i), unknown 



Fig. 4. Shoulder-bones of Ornithorhynchus : 



c, c, claTicles ; i, interclavicle ; 6, breast-bone ; sr, sternal or 



breast-bone ribe, as in birds. 



in any other mammals ; and here, again, we find a 

 character which is decidedly reptile-like and bird-like, 

 and which is not seen in other mammals. Professor 

 Flower tells us that the shoulder-girdle of these quadrupeds 

 " differs widely in many points from that of any other 

 mammal, and far more resembles that of the Lizards." 



The jaws of the Ornithorhynchus are prolonged to form 

 a flattened homy bill (Fig. 1), on the upper aspect of which 

 the nostrils are seen. It is the possession of this bill which 

 has given origin to the name " duck-billed," applied to 

 this animal. The Echidna possesses no such structtire, but 

 has simply a flexible snout. 



There also exist in the internal anatomy of these 

 curious animals certain characters which relate them to 

 the birds and reptiles. For example, the bones of the 

 head are firmly ossified together, as in birds, and the 

 sutures, or lines of union of the skull-bones, do not 

 persist, as is usually the case in quadrupeds, whilst 

 the hollow of the haunch-bones (Fig. 2, d), in which the 

 head of the thigh works to form the hip-joint, is not 

 fuUy ossified, and thus comes to resemble the similar 

 structure in birds and crocodiles. The ears of these 

 lower quadrupeds dift'or from those of other mammals 

 in not possessing a spiral arrangement of that part of the 

 organ named the cocldi'a. As in very many reptiles, the 

 upper, or front, or neck-ribs of these quadrupeds long 

 remain as separate bones ; and the same remark holds good 

 of the curious little pivot {odontoid process) on which the 

 head turns. This pivot in quadrupeds is firmly joined to 

 the second bone of the neck : but in the " Monotremes," 

 as in reptiles, it remains separate and distinct till a very 

 late period — if, indeed, it becomes ossified at all. 



The internal anatomy likewise reveals characters of bird 

 and reptile life which can only be alluded to here. The 

 arrangements of the internal organs in many respects 

 present the closest likeness to the anatomy of birds and 

 reptiles, and this is particularly the case with those struc- 

 tures in the quadrupeds which represent the egg-producing 

 organs of the bird and reptile. Even the typical mamma- 

 lian characters are but feebly represented in these lowest 

 quadrupeds. We know that the young, although born 

 alive, as in quadruped life at large, are provided with a 

 homy knob on the upper jaw, such as is seen in the young 

 bird ; and no teats exist in the milk-glands of these forms, 

 a feature represented in all other members of their class. 



Summing up the inferences to be drawn from our brief 

 study of the lowest quadrupeds, we may legitimately hold, 

 firstly, that they are of essentially lower structure than 

 other mammals ; secondly, that all the points in which 

 they evince this inferiority ally them, at the same time, to 

 birds and reptiles ; and thirdly, that the only feasible ex- 

 planation of the differences in question is that which regards 

 them as arising from the nearer relationship — the result 

 of heredity and descent — which these lowest quadrupeds 

 present to birds and reptiles. 



In a concluding paper, I shall strive to show the nature 

 of the links which unite the A'ertebrate animals to their 

 lower and Invertebrate neighbours. 



CAMBRIDGE AND OXFORD STYLES. 



{To an old Club Captain.) 



DEAR SIR, — As the stroke oar of the winning boat in 

 the Oxford and Cambridge race, 184.5-46, and, I be- 

 lieve, the introducer of the slow recovery by which both 

 races were won (though I can really, however, say that only 

 of the first, for, in the latter race Milman pulled very 

 nearly my stroke), I wish to say how much I approve of 

 all you have written in Knowlkdof. ; and to remark that 

 Cambridge loses now because they both hurry forward and 

 go too far back — at least, this latter is often a fault with 

 them. The rapid recovery is always a fault, and, I think, 

 the most exhausting fault that can be made either in the 

 old boat or the new boat, but very particularly so in the 

 new boat. — Yours faithfully, C. G. Hill. 



Special Notice. — Fonrpence each will be paid by the Publishers 

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