The Holocephali, or Chimsras 



565 



and the huge jet-black Chimara piirpiirascens in Hawaii and 

 Japan. None of these species are valued as food, but all impress 

 the spectator with their curious forms. 



The fossil Chimccridce, 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 earhest of chimieroid remains has 



4 



t3^^ 



"^"'«m, ,_ 



Fig. 352. — Elephant-fish, Chimcera colliei Lay & Bennett. Monterey. 



been described by Dr. Charles D. Walcott * from Ordovician 

 or Lower Silurian rocks at Canon 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 CJiimccridcB are mainly confined to the 

 rocks of the Mesozoic and subsequent eras. Ischyodiis priscus 

 iavitus) of the iower Jura resembles a modern chimasra. 

 Granodus oweni is another extinct chimera, and numerous 

 fin-spines, teeth, and other fragments in the Cretaceous and 

 Eocene of America and Europe are referred to EdapJiodon. A 

 species of Chinicsra has been recorded from the Pliocene of 

 Tuscany, and one of Callorhynchus from the greensand of New 

 Zealand. Other American Cretaceous genera of chimieroids are 

 Adylognathus, Bryactiniis, Isotcrnia, Leptomylus and SpJiagepcca. 

 Dental plates called Rhynchodus are found in the Devonian. 



Rhinochimaeridse. — The most degenerate oi existing chima^ras 

 belong to the family of Rhinochimasridcc , characterized by the 

 long flat soft blade in which the snout terminates. This struc- 



* Bulletin Geol. Soc. America, 1S92. 



