Temperature and Ve^'tebrcz 33 



ther. He noted that among the Labridoe, the species of 

 temperate waters had more vertebra than those of the tropics. 

 He says :''■'• 



Iti those genera of LabridcF which are composed entirely or for the 

 greater part of tropical species the vertebral column is composed of 

 twenty-four vertebrse, whilst those which are chiefly confined to the 

 temperate seas of the northern and southern hemispheres have that 

 number increased in the abdominal and caudal portions. 



Gill, 1863. — Shortly after, in a review of Dr. Giinther's 

 work on the Labroids.f Dr. Theodore Gill showed that this 

 generalization was not confined to the labroids alone, but 

 that "it ma}' also be extended to other families. * * * This 

 generalization is applicable to the representatives of acan- 

 thopterj'gianj families generally, and can be considered in 

 connection with the predominance of true malacopterygian§ 

 fishes in northern waters, fishes in which the increase in the 

 number of vertebrae is a normal feature." 



Gill, 1864. — Later, II Dr. Gill remarked that the increase in 

 the number of vertebree of Sebastes, a genus peculiar to the 

 northern seas, affords an excellent example of the truth of the 

 generalization claiming an increased number of vertebrae for 

 the cold-water representatives of acanthopterygians. 



Jordan, 1886. — In 1886, in a paper before the Indiana Acad- 

 emy of Sciences,^ the present writer showed that in very 

 many families the number of veterbrse decreases as we ap- 

 proach the tropics. So constant is this relation that it was 

 thought that it might almost be termed a law. The writer 

 could however suggest no adequate cause by the operation of 

 which such changes are brought about. 



Jordan and Goss, 1889. — In a study of the flounders, in 

 1889,** a table was given showing the numbers of vertebrae in 



* Catalogue of the Fishes of the British Museum, vol. iv, p. 65. 



f On the Labroids of the Western Coast of North America, Proc. Ac. 

 Nat. Sc, Phila., 1863, p. 221. 



J Spiny-rayed. 



'i Soft-rayed ; here including the anacanthine fishes. 



II Proceedings Academy Natural Science, Phila., 1864, 147. 



Tf Still unpublished. 



** A Review of the Flounders and Soles (Pleuronedida) of America 

 and Europe, by David S. Jordan and David K. Goss. 



