460 PROF. ST. GEORGE MIVART ON THE 
axial system, as do the epipleural spines of fishes, e.g. those so well developed in the 
Herring. He appears to have considered the limb-girdles as hypertrophied radial 
parts left after others primitively (or ideally) existing with them had disappeared. He 
says they are formed “ under the tegumentary covering, and therefore external to the 
proper visceral wall of the body.” The limbs of higher animals than fishes he regards as 
formed in the following way :—‘‘ By atrophy or otherwise, one or more of the segments 
in the successive transverse rows of actinapophysial elements disappear, so as to leave in 
Man one in the arm, two in the next row for the coracoid and clavicle, and one in the 
proximal row for the scapula.” He is “inclined to believe that the coracoid is an acti- 
napophysial segment between the humerus and scapula, prolonged downwards towards 
the hemal margin of the body; that the scapula is a proximal element, elongated 
towards the neural margin of the body; that the clavicle is the only other retained 
element in the same transverse row as the coracoid ”}. 
In 18712, Professor Humphrey, recalling to recollection the fact that the dorsal and 
ventral mid lines of the trunk are formed by the junction of the bifold amine dorsales 
and ventrales respectively, thence deduced the conclusion that the azygos fins of fishes 
must be of bifold origin. He also puts forward the view that the pectoral and ventral 
fins are but certain portions of the inferior azygos fins, which are separated (or, rather, 
hindered from uniting) by the interposed body-cavity. Thus he regards the pelvic 
bones of the ventral fins and the so-called “ carpals” of the pectoral fins as modified 
interspinous bones. 
In this way the limbs of higher animals would be (as Maclise had before represented 
them to be) modified portions of the ventral azygos fin. 
In 1872, Professor Gegenbaur * threw out the suggestion that the shoulder-girdle was 
a modified arch of similar nature to the branchial arches (7. ¢. a part of the visceral 
skeleton), and that the limbs may have been formed from the diverging rays of such 
an arch. This view he has confirmed and supported in more recent publications in 
18744 and 1876°. The azygos fins of fishes are considered by him to be parts seg- 
mented off from the neural or hemal spines of the vertebral column °. 
In April, 1877, Professor Macalister, in treating’ of the development of the muscular 
system, and in a later publication, has spoken of vertebrate limbs in such a way as 
IER oy lstils 
> Cambridge Journal of Anatomy and Physiology, vol. v. (second series, vol. iv.) page 58, plate ii. 
% Untersuchungen, Heft 3, p. 181, note. 
4 Grundriss d. vergl. Anat. page 494, His words are, ‘Das ganze einem Fiederblatte ihnliche Skelet- 
eebilde stimmt auffallend mit manchen Stiitzapparaten der Selachier-Kiemen, und liisst dadurch ein Streif Licht 
auf die Frage yon der Phylegenese der Glicdmassenbildungen fallen.” 
> Morphologisches Jahrbuch, ii. Band, drittes Heft, p. 417, fig. 4. 
6 Grundriss der vergl. Anatomie, 1874, p. 488. 
7 Dublin Medical Journal for April 1877. 
* Address to British Association of 1877, reported in ‘ Nature.’ 
