. Elements of Comparative Anatomy. Fig. 257. Hyoid, and brau- cliial arches of a larva of Salamandra maculosa. h Hyoid arch, c c Supports of the branchial arches. d Appendage of the Fig. 258. Hyoid of Bufo cincreus. n Copula, i Cor- nua of the hyoid. c Eeui- nants of the branchial arches (after Duges). present at tlie same a gradual change in this apparatus. It is retained in the Perennibranchiata, and undergoes slight changes only in the Derotremata. It is made up of four or five pairs of arches; the first of which, as in Fishes, forms a hyoid arch (Fig. 257,6). The suc- ceeding arch
. Elements of Comparative Anatomy. Fig. 257. Hyoid, and brau- cliial arches of a larva of Salamandra maculosa. h Hyoid arch, c c Supports of the branchial arches. d Appendage of the Fig. 258. Hyoid of Bufo cincreus. n Copula, i Cor- nua of the hyoid. c Eeui- nants of the branchial arches (after Duges). present at tlie same a gradual change in this apparatus. It is retained in the Perennibranchiata, and undergoes slight changes only in the Derotremata. It is made up of four or five pairs of arches; the first of which, as in Fishes, forms a hyoid arch (Fig. 257,6). The suc- ceeding arches are united to a com- mon copula. The posterior ones do not severally ex- tend as far as it, hut are connected together on either side. In correlation with the reduction of the arches, the co- pulas are increased in size. The only portion which re- mains complete after metamorpho- sis is the hyoid (Fig. 258, h). It is united with the copula {a), which is generally of some size, and which is converted into_ the body of the hyoid. A larger piece of the second arch is retained in the Salamandrina, and a small portion of the third arch; in the Anura, however, there is a cartilaginous plate, which is made up of all the branchial arches on either side, and which fuses with the copula into one piece. Eod-shaped pieces (columellee), which are developed from the ends of the primitively paired plates, are attached to this (Fig. 258, c). The changes in the branchial skeleton, which are perceptible when it changes its function, afford a striking example of the great influence which adaptation to external conditions of life exercises on the internal organisation. § 356. The degeneration which is seen in individuals among some of the Amphibia is an inherited arrangement in the higher classes. Except those parts which enter into the composition of the auditory organ, all the parts which were developed at one time from the large branchial skeleton of Fishes, are converted into that support
Size: 1517px × 1647px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, bookcentury1800, bookdecade1870, bookpublisherlondonmacmillan
