1890.] The Homologies of the Fins of Fishes. 405 
above. The bone connected with the skull is, as has been said 
before, named the posttemporal by Parker. The clavicle of 
Gegenbaur is the coracoid of Owen,’ while his scapula is Owen's 
ulna, and his coracoid the radius. As Gill remarks, Owen first 
sought to determine an ulna and radius, and then identified the 
other bones from their relations to it. (Figs. 3 and 4.) 
But, even though the terms used by Gegenbaur be adopted as 
representing most nearly the correspondences between the parts 
of the shoulder-girdle of the Dipnoi and Stapedifera on the one 
hand, and those of the Teleostomata, Crossopterygia, Podopterygia, 
and Elasmobranchs on the other, an exact homology is not yet 
positively assured. Hence Gill , 
has subsequently termed Gegen- 
baur’s scapula hypercoracoid, and 
his coracoid the hyopocoracoid. 
In the ventral fins the process 
of concrescence is carried to a 
considerable extent in Polypterus 
and the Chrondrostei, and farther 
still in Amia, Lepidosteus and the 
Teleostomata, which agree in the 
possession of a single large elon- 
gated element proximal to the 
basilars in each ventral. To this 
base areattached four long basilar 
rays in Polypterus, nine in 4c- 
cipenser brevirostrum, and three = Fic 4.—Satmo fario, left shoulder-girdle ; 
minute ossicles in the Teleosto- se taena De ia t ieg paprik at; 
mata. The elongated supporting Co(CI), coracoid; Ra, basilars; Z, scap- 
bone is styled by Thacher a “eet: 25. TS mny. 
pubis, and Wiedersheim has recently shown that it isa part of ` 
the pelvis, and, being preacetabular, is the homologue of the pubis.” 
The conclusion that can be arrived at from a study of both the 
pectoral and ventral fins is that the limbs of all air-breathing 
mammals or Stapedifera (possessed of a stapes) form a group 
9 Comp. Anat. and Physiol. of Vertebrates, Vol. I., p. 106. 
10 Anatomischer Anzeiger, 1889, IV. 

