Tempe7'ature and Vertebras 23 



California,* Japan, Chili, and the Cape of Good Hope, have 

 in all their species 27 vertebra;, while in the single arctic 

 genus there are 3i.t An antarctic genus| bearing some 

 relation to Sebastes has 39. 



Allied to the Scorpmnidce, but confined to the tropical or 

 semi-tropical seas, are the Platycephalida;, with 27 vertebra;, 

 and the Cephalacanthida; with but 22. In the deeper waters 

 of the tropics are the Peristediida , with 33 vertebrge, and ex- 

 tending farther north, belonging as much to the temperate as 

 to the torrid zone, is the large family of the Triglida,% in 

 which the vertebras range from 25 to 38. 



The fa.m\\y of Agonida,\\ with 36 to 40 vertebrae, is still 

 more decidedly northern in its distribution. Wholly confined 

 to northern waters is the great family of the Cottida:,^ in 

 which the vertebrae ascend from 30 to 50. Entirely polar and 

 often in deep waters are the Liparididce** an offshoot from 

 the CottidcB, with soft, limp bodies, and the vertebrae 35 to 65. 

 In these northern forms there are no scales, the spines in the 

 fins have practically disappeared, and only the anatomy shows 

 that they belong to the group of spiny-rayed fishes. In the 

 Cydoptctidce ,'\j likewise largely arctic, the body becomes short 

 and thick, the backbone inflexible, and the vertebrae are again 

 reduced to 28. In most cases, as the number of vertebrae in- 

 creases, the body becomes proportionally elongate. As a 

 result of this, the fishes of arctic waters are, for the most part, 

 long and slender; and not a few of them approach the form of 

 eels. In the tropics, however, while elongate fishes are com- 

 mon enough, most of them (always excepting the eels) have 

 the normal number of vertebrae, the greater length being due 



* Sebastichthys and its offshoots Sebastodes, Sebastopsis, etc., the 

 "rock cod " of California. fThe rosefish, Sebastes and its offshoot, 



the genus or subgenus, Sebastolobus. X Agriopus 



^The gurnards and sea robins. The lowest numbers are found in the 

 Americar genus Prionotus, which is chiefly tropical, the highest in 

 Lepidotrigla, which is confined to southern Europe. 



II Sea poachers, alligator fishes, etc. "[Sculpins, Miller's thumbs, etc. 



** Sea snails. ft Lumpfishes, 



