459, " 25, _for_ thme _read_ them 467, " 14, for _Typhogobius_ read _Typhlogobius_ 472, lines 34, _omit_ "but never in the United States". 35, Specimens of _Regalecus_ have been taken at Anclote Key, Florida, and at the Tortugas. 580, col. 3, line 17, _for_ 165 _read_ 105 The adoption of the Code of the International Congress of Zoology necessitates a few changes in generic names used in this book. Thus _Amia_ (ganoid) becomes _Amiatus_ _Apogon_ becomes _Amia_ _Scarus_ becomes _Callyodon_ _Teuthis_ becomes _Hepatus_ _Acanthurus_ becomes _Monoceros_ _Paramia_ becomes _Cheilodipterus_ _Centropomus_ (_Oxylabrax_) remains _Centropomus_ _Lucioperca_ (_Centropomus_) becomes _Sander_ _Pomatomus_ (_Cheilodipterus_) remains _Pomatomus_ _Nomeus_ (_Gobiomorus_) remains _Nomeus_ _Galeus_ (_Galeorhinus_) remains _Galeus_ _Carcharias_ (_Carcharhinus_) remains _Carcharias_ Footnote 1: For most of this list of errata I am indebted to the kindly interest of Dr. B. W. Evermann. CHAPTER I THE GANOIDS =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 (ακτίς, ray; πτερόν or πτερύξ, 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.