84 SHOULDER-GIRDLE AND BREAST-BONE. 



which are held up to view for weeks and months ; but in the low Cartilaginous Fishes we see 

 gigantesque figures which are never taken down. Hence the necessity for both " gradational" 

 and " developmental" morphology ; and these two divisions of one science are nothing if not 

 mutual; for neither is development to be studied without gradation, nor gradation without 

 development, but both must be worked out by the same observer, and the results of both must 

 intermarry in the same intellect before that birth of thought can take place which can be called 

 perfect science. I shall have to refer to the Amphibians again and again in describing the struc- 

 ture of the nobler antitypes which they in sundry ways foreshadow ; but before leaving the 

 Amphibia I shall give the views of Duges on the homologies of the Shoulder-girdle and Sternum 

 of the Frog. 



ANT, DuoJis, ' EecJierches sur TOstedogie et la Mydogie dcs Batracictis.' 4to, Paris, 1834. 



In his section on the Shoulder (p. 62), he remarks, " We have here to examine six distinct pieces 

 (figs. 22 31) , a of which one has often been attributed to the Sternum, and of which another has only 

 been described by Mertens. We will indicate, first, the names we have thought proper to give to these 

 parts, and justify their application subsequently. 



1. Ad-scapulum \supra-scapula~], " omolite" of Geoffrey, fig. 22, No. 29 2 ), the superior portion of 

 the omoplate [scapula], always less ossified and thinner than the next ; it is, nevertheless, never altogether 

 cartilaginous in the adult; yet it is perceptible that the ossification propagates itself from the anterior 

 and from the inferior border; it is then one single and individual piece, whether it is only in part 

 ossified, as in Toads, Sonneurs (Ringers, Bell-frogs), and Rainettes (Little Frogs), or is altogether ossified 

 (Frogs). It is this which refutes the argument by which Cuvier has opposed the opinion of M. Geoffroy, 

 who sees in this piece the representation of the superadded cartilage of the scapula of young Mam- 

 mifers. But this piece has also, as Cuvier truly says, its cartilage, but not distinct and separate not 

 connected with the osseous part as a true epiphysis. 



2. Scapulum (scapula. No. 30 3 ), always shorter and thicker than the preceding piece, and longer 

 than broad in the greater number of the Anourous Batrachia; but broader than long, and consequently 

 very short, in the Bufo igneus and the two " obstetricans :" it is as though bifurcated at its] inferior 

 extremity or border, where it makes a part of the glenoid cavity. Of the two branches of this 

 bifurcation, the internal and posterior [post-scapula'] is clearly the coracoid apophysis of the Mammifers 

 of Man, for example [not so; it forms the neck and most of the ylenoid cavity'] ; the external and 

 anterior (praR-scapula) is clearly the acromion or its commencement, the spine of the scapula. 



3. The groove which separates these two eminences [scapular fenestra'] is converted into a hole 

 by a piece which long remains cartilaginous, but which finally ossifies separately, and appears as if 

 intercalated between the scapula and the other pieces forming the shoulder (31*). This piece, which I 

 call the paraglenal [endosteal bone in cartilaginous symphysis], and which was recognised by Mertens, 

 represents the coraco-acromial ligament of Man, and, like it, serves to complete the articular cavity 

 which receives the head of the humerus. It is of large size in the common Toad and in the Green 

 Frog, but I have not, been able to distinguish it in the dry skeleton of the Bufo fuscus. 



1 I shall not reproduce the figures from Duges' work, but refer the reader to my own plates. 



3 See Plate V, fig. 11, s. sc. 



3 See Plate V, fig. 11, sc., p. sc. 



* This bony patch is shown in Plate V, figs. 9 and 15, gl. 



