Numerous fossil genera related to _Elops_ are found in the Cretaceous and Tertiary rocks. _Holcolepis lewesiensis_ (wrongly called _Osmeroides_) is the best-known European species. Numerous species are referred to _Elopopsis_. _Megalops prisca_ and species of _Elops_ also occur in the London Eocene. In all these the large parietals meet along the median line of the skull. In the closely related family of _Spaniodontidæ_ the parietals are small and do not meet. All the species of this group, united by Woodward with the _Elopidæ_, are extinct. These fishes preceded the _Elopidæ_ in the Cretaceous period. Leading genera are _Thrissopater_ and _Spaniodon_, the latter armed with large teeth. _Spaniodon blondeli_ is from the Cretaceous of Mount Lebanon. Many other species are found in the European and American Cretaceous rocks, but are known from imperfect specimens only. _Sardinius_, an American Cretaceous fossil herring, may stand near _Spaniodon_. _Rhacolepis buccalis_ and _Notelops brama_ are found in Brazil, beautifully preserved in concretions of calcareous mud supposed to be of Cretaceous age. The extinct family of _Pachyrhizodontidæ_ is perhaps allied to the _Elopidæ_. Numerous species of _Pachyrhizodus_ are found in the Cretaceous of southern England and of Kansas. =The Albulidæ.=—The _Albulidæ_, or lady-fishes, characterized by the blunt and rounded teeth, are found in most warm seas. _Albula vulpes_ is a brilliantly silvery fish, little valued as food. The metamorphosis (see Fig. 112, Vol. I) which the larva undergoes is very remarkable. It is probably, however, more or less typical of the changes which take place with soft-rayed fishes generally, though more strongly marked in _Albula_ and in certain eels than in most related forms. Fossils allied to _Albula_, _Albula oweni_, _Chanoides macropomus_, are found in the Eocene of Europe; _Syntegmodus altus_ in the Cretaceous of Kansas. In _Chanoides_, the most primitive genus, the teeth are much fewer than in _Albula_. _Plethodus_ and _Thryptodus_, with peculiar dental plates on the roof and floor of the mouth, probably constitute a distinct family, _Thryptodontidæ_. The species are found in European and American rocks, but are known from imperfect specimens only. [Illustration: FIG. 31.—The Lady-fish, _Albula vulpes_ (Linnæus). Florida. ] =The Chanidæ.=—The _Chanidæ_, or milkfishes, constitute another small archaic type, found in the tropical Pacific. They are large, brilliantly silvery, toothless fishes, looking like enormous dace, swift in the water, and very abundant in the Gulf of California, Polynesia, and India. The single living species is the _Awa_, or milkfish, _Chanos chanos_, largely used as food in Hawaii. Species of _Prochanos_ and _Chanos_ occur in the Cretaceous, Eocene, and Miocene. Allied to _Chanos_ is the Cretaceous genus _Ancylostylos_ (_gibbus_), probably the type of a distinct family, toothless and with many-rayed dorsal. [Illustration: