This suborder is represented in the living fauna by one family only, _Chimæridæ_; it forms a passage to the following order of fishes, the Ganoids. In external appearance, and with regard to the structure of their organs of propagation, the Chimæras are Sharks (See Fig. 96, p. 184). The males are provided with “claspers” in connection with the ventral fins, and the ova are large, encased in a horny capsule, and few in number; and there is no doubt that they are impregnated within the oviduct, as in Sharks. Chimæras are naked, but, as in _Scylliidæ_, very young individuals possess a series of small “placoid” spines, which occupy the median line of the back, and remind us of similar dermal productions in the Rays. The males, besides, are provided with a singular erectile appendage, spiny at its extremity, and received in a groove on the top of the head. On the other hand, the relations of the Chimæras to the Ganoid, and, more especially, Dipnoous type become manifest in their notochordal skeleton and continuity of cranial cartilage. The spine in front of the first dorsal fin is articulated to the neural apophysis, and not merely implanted in the soft parts, and immovable as in Sharks. A cartilaginous operculum makes its appearance, and the external gill-opening is single. The dentition is that of a Dipnoid, each “jaw” being armed with a pair of broad dental plates, with the addition of a pair of smaller cutting teeth in the upper “jaw.” Fossils of similar dental combination are not rare in strata, commencing from the Lias and the bottom of the Oolitic series; but it is impossible to decide in every case whether the fossil should be referred to the Holocephalous or Dipnoous type. According to Newberry, Chimæroid fishes commence in the Devonian with _Rhynchodus_, the remains of which were discovered by him in Devonian rocks of Ohio. Undoubted Chimæroids are _Elasmodus_, _Psaliodus_, _Ganodus_, _Ischyodus_, _Edaphodon_, and _Elasmognathus_, principally from mesozoic and tertiary formations. Very similar fossils occur in the corresponding strata of North America. A single species of _Callorhynchus_ has been discovered by H. Hector in the Lower Greensand of New Zealand. The living Chimæras are few in number, and remain within very moderate dimensions, probably not exceeding a length of five feet, inclusive of their long filamentous, diphycercal tail. They are referred to two genera. CHIMÆRA.--Snout soft, prominent, without appendage. The dorsal fins occupying the greater part of the back, anterior with a very strong and long spine. Longitudinal axis of the tail nearly the same as that of the trunk, its extremity being provided with a low fin above and below, similar in form to a dorsal and anal fin. Anal fin very low.