22 David Starr Jordan 



other respects. The range of distribution of these fishes is 

 chiefly though not quite wholly confined to the tropics. 



A very few spiny-rayed families are wholly confined to the 

 northern seas. One of the most notable of these is the family 

 of viviparous surf fishes, "i^ of which numerous species abound 

 on the coasts of California extending to Oregon, and Japan, 

 but which enter neither the waters of the frigid nor the torrid 

 zone. These fishes seem to be remotely connected with the 

 LabridcE\ of the tropics, but no immediate proofs of their 

 origin exist. The surf fishes have from 32 to 42 vertebrae, 

 numbers which are never found among tropical fishes of simi- 

 lar appearance or relationship. 



The fact of variation in the numbers of vetebrae was first 

 noticed among the LabridcB. Here the facts are most strik- 

 ing. In the genera of LabridcB inhabiting northern Europe 

 and the New England waters {Lab7'us, Acantholabrus, Ctenola- 

 brus, Tatitoga, ) t\i<tr& are 38 to 41 vertebrae, in the Mediter- 

 ranean forms {Symphodus, etc.,) 30 to 33, in certain semi- 

 tropical genera { Lachnolaivius , Harpe, Trochocopus) 27 to 29, 

 while in those genera which chiefly abound about the coral 

 reefs {Scarics, Sparisoma, Xyrichthys, Juiis, Tkalassoma, Hal- 

 ichares) the number is from 23 to 25. 



Equally striking are the facts in the great group of Caiaph- 

 radi, or mailed-cheek fishes, a tribe now divided into several 

 families, diverging from each other in various respects, but 

 agreeing in certain peculiarities of the skeleton. J 



Among these fishes the famil}' most nearly- related to ordi- 

 nary fishes is that of the ScorpcsnidcE .% 



This is a large family containing many species, fishes of 

 local habits, swarming about the rocks at moderate depths in 

 all zones. The species of the tropical genera have all 24 ver- 

 tebrae. || Those genera chiefly found in cooler waters, as in 



* Embiotocid(Z. 



t Wrasse fishes, old wives, parrot fi.shes, cunners, tautogs, redfishes, 

 senoritas, etc. 



J Notably by the formation of a bony "stay" to the preopercle by 

 the backward extension of one of the suborbital bone.s. 



§ Sea scorpions, rockfishes, "rock cod," rosefishes, etc. 



^Scorpcena, Sebastoplus, Pterois, Synanceia, Synancidium, etc. 



