A Guide to the Study of Fishes, Volume 2 (of 2)

A Guide to the Study of Fishes, Volume 2 (of 2)

VARIATIONS IN THE COLOR OF FISHESThe Oniokose or Demon Stinger, Inimicus japonicus (Cuv. and Val.), from Wakanoura, Japan. From nature by Kako Morita.Surface coloration about lava rocks.Coloration of specimens living among red alg.Coloration in deep water; Inimicus aurantiacus (Schlegel). Subclass Actinopteri.In our glance over the taxonomy of the earlier Chordates, or fish-like vertebrates, we have detached from the main stem one after another a long series of archaic or primitive types. We have first set off those with rudimentary notochord, then those with retrogressive development who lose the notochord, then those without skull or brain, then those without limbs or lower jaw. The residue assume the fish-like form of body, but still show great differences among themselves. We have then detached those without membrane-bones, or trace of lung or air-bladder. We next part company with those having the air-bladder a veritable lung, and those with an ancient type of paired fins, a jointed axis fringed with rays, and those having the palate still forming the upper jaw. We have finally left only those having fish-jaws, fish-fins, and in general the structure of the modern fish. For all these in all their variety, as a class or subclass, the name Actinopteri, or Actinopterygii, suggested by Professor Cope, is now generally adopted. The shorter form, Actinopteri, being equally correct is certainly preferable. This term (, ray; or , fin) refers to the structure of the paired fins. In all these fishes the bones supporting the fin-rays are highly specialized and at the same time concealed by the general integument of the body. In general two bones connect the pectoral fin with the shoulder-girdle. The hypercoracoid is a flat square bone, usually perforated by a foramen. Lying below it and parallel with it is the irregularly formed hypocoracoid. Attached to them is a row of bones, the actinosts, or pterygials, short, often hour-glass-shaped, which actually support the fin-rays. In the more specialized forms, or Teleosts, the actinosts are few (four to six) in number, 2but in the more primitive types, or Ganoids, they may remain numerous, a reminiscence of the condition seen in the Crossopterygians, and especially in Polypterus. Other variations may occur; the two coracoids sometimes are imperfect or specially modified, the upper sometimes without a foramen, and the actinosts may be distorted in form or position. ......Buy Now (To Read More)

Product details

Ebook Number: 51702
Author: Jordan, David Starr
Release Date: Apr 9, 2016
Format: eBook
Language: English