112 TEMPEllATUKE AND FISH VERTEBRAE — JORDAN. 



NUMBERS OF VERTEBRA. 



GANOID FISHES. 



It may be takeu for granted tliat the ancestry of the various modern 

 types of bony fishes is to be sought among the Ganoids. All the fossil 

 forms in this group have a notably large number of vertebra?. The 

 few now living are nearly all fresh-water fishes, and among these, so 

 far as known, the numbers range from G5 to 110.* 



SOFT-RAYED FISHES. 



Among the Teleostei or bony fishes, those which first appear in geo- 

 logical history are the Isosjyoridyli, the allies of the salmon and herring. 

 These have all numerous vertebrie, small in size, and none of them in 

 any notable degree modifledt or specialized. In the northern seas 

 Isospondyli still exceed all other fishes in number of individuals. They 

 abound in the depths of the ocean, but there are comparatively few of 

 them in the tropics. 



The ISalmonid(V^ which inhabit the rivers and lakes of the northern 

 zones have from GO to 65 vertebrte. The Scopeliclw^ Sfoyniatidw, and 

 other deep-sea analogues have from 40 upwards in the few species in 

 which the number has been counted. 



The group of Ghipcid(c^ is probably nearer the primitive stock of 

 Isospondyli than the salmon are. This group is essentially northern 

 in its distribution, but a considerable number of its members are found 

 within the tropics. The common herring|| ranges farther into the Arc- 

 tic regions than any other. Its vertebiic are 50 in number. In the 

 shad,^ a northern species which ascends the rivers, the same number 

 has been recorded. 



The sprat** and sardine tt ranging farther south, have from 48 to 50, 

 while in certain small herring|| which are strictly confined to tropical 

 shores the number is but 40. 



Allied to the herring are the anchovies, mostly tropical. The north- 

 ernmost species, §§ the common anchovy of Europe, has 4G vertebra?. A 

 tropical species |||| has 41 segments. 



There are, however, a few soft-rayed fishes^ Vf confined to the tropical 

 seas in which the numbers of vertebrie are still large, an exception to 



* Sixty-seven in Polijpterus, 110 in Calamoichthys, 95 in Amia, etc. 



t As is indicated by the name Isospondyli, from idoi, equal, dnovdvXoS, vertebra. 



t Salmon, trout, grayling, wbitefish, etc. 



^Herring, shad, sprat, sardine, and their allies. 



II Clupea hareiujus. H Cliipea alosa, the European shad. 



** Clupea sprattiis. tt Clupea pilchardus. 



U Harcngula macrophthalma. ^§ StoIc2)horus cnclirasicolus. 



III! SloUphonts hrowni. 



nil Among those are Albiila vulpes, the bonefish, with 70 vertebra^. Flops saurtis, the 

 ten-pounder, with 72, the Grande ficaille (Megalops cuprinoidin) with 57, and Chanoa 

 chanos with 72. 



