The rhombic enameled scales are highly specialized and held together as a coat of mail by peg-and-socket joints. The most extreme form is _Platysomus_, with the body very deep. _Platysomus gibbosus_ and other species occur in the Permian rocks of Germany. _Cheirodus_ is similar to _Platysomus_, but without ventral fins. _Eurynotus_, the most primitive genus, is remarkable for its large pectoral fins. _Eurynotus crenatus_ occurs in the Subcarboniferous of Scotland. Other genera are _Mesolepis_, _Globulodus_, _Wardichthys_, and _Cheirodopsis_. [Illustration: FIG. 3.—_Eurynotus crenatus_ Agassiz, restored. Carboniferous. Family _Platysomidæ_. (After Traquair.) ] Some of the _Platysomidæ_ have the interneural spines projecting through the skin before the dorsal fin. This condition is found also in certain bony fishes allied to the _Carangidæ_. =The Dorypteridæ.=—_Dorypterus hoffmani_, the type of the singular Palæozoic family of _Dorypteridæ_, with thoracic or sub-jugular many-rayed ventrals, is Stromateus-like to all appearance, with distinct resemblances to certain Scombroid forms, but with a heterocercal tail like a ganoid, imperfectly ossified back-bone, and other very archaic characters. The body is apparently scaleless, unlike the true _Platysomidæ_, in which the scales are highly developed. A second species, _Dorypterus althausi_, also from the German copper shales, has been described. This species has lower fins than _Dorypterus hoffmani_, but may be the adult of the same type. _Dorypterus_ is regarded by Woodward as a specialized offshoot from the _Platysomidæ_. The many-rayed ventrals and the general form of the body and fins suggest affinity with the _Lampridæ_. [Illustration: FIG. 4.—_Dorypterus hoffmani_ Germar, restored. (After Hancock and Howse.) ] =Dictyopygidæ.=—In the _Dictyopygidæ_ (_Catopteridæ_), the body is gracefully elongate, less compressed, the heterocercal tail is short and abruptly turned upwards, the teeth are sharp and usually hooked, and the bony plates well developed. Of this group two genera are recognized, each containing numerous species. In _Redfieldius_ (= _Catopterus_ Redfield, not of Agassiz) the dorsal is inserted behind the anal, while in _Dictyopyge_ this is not the case. _Redfieldius gracilis_ and other species are found in the Triassic of the Connecticut River. _Dictyopyge macrura_ is found in the same region, and _Dictyopyge catoptera_ and other species in Europe.