222 The Holocephali, or Chimeras 
and the huge jet-black Chimera purpurascens in Hawaii and 
Japan. None of these species are valued as food, but all impress 
the spectator with their curious forms. 
The fossil Chimeride; although numerous from Triassic 
times and referred to several genera, are known chiefly by their 
teeth with occasional fin-spines, frontal holders, or impressions 
of parts of the skeleton. The earliest of chimzroid remains has 
Fie. 158.—Elephant-fish, Chimera colliei Lay & Bennett. Monterey. 
been described by Dr. Charles D. Walcott * from Ordovician 
or Lower Silurian rocks at Cafion City, Colorado. Of the species 
called Dictyorhabdus priscus, only parts supposed to be the 
sheath of the notochord have been preserved. Dr. Dean thinks 
this more likely to be part of the axis of a cephalopod shell. 
The definitely known Chimeride are mainly confined to the 
rocks of the Mesozoic and subsequent eras. Ischyodus priscus 
(avitus) of the sower Jura resembles a modern chimera. 
Granodus owent is another extinct chimzra, and numerous 
fin-spines, teeth, and other fragments in the Cretaceous and 
Eocene of America and Europe are referred to Edaphodon. A 
species of Chimera has been recorded from the Pliocene of 
Tuscany, and one of Cal’orhynchus from the greensand of New 
Zealand. Other American Cretaceous genera of chimzeroids are 
Mylognathus, Bryactinus, Isotenia, Leptomylus, and Sphagepea. 
Dental plates called Rhynchodus are found in the Devonian. 
Rhinochimeride.—The most degenerate of existing chimeras 
belong to the family of Rhinochimeride, characterized by the 
long flat soft blade in which the snout terminates. This struc- 
* Bulletin Geol. Soc. America, 1892. 
