No. 645] VERTEBRA OF FISHES 



nigrum). Schmidt (1921) has lately studied such annual 

 fluctuations in great detail in Zoarces, and has induced 

 like changes by experimental control of temperature in 

 Lebistes (1919<i, 1919&) and Salmo (1921). I have ob- 

 tained similar experimental results for coregonine fishes 

 and for Esox lucius (data yet unpublished). 



On the other hand it has been clearly demonstrated in 

 a number of cases that fine "racial" differences are in- 

 herited. Thus Schmidt (1917a, 19175, 1918, 1920, 1921> 

 has determined by his ''offspring analyses" that a high 

 degree of positive correlation holds between the number 

 of segments and other features of the maternal parent 

 and the unborn embryos of Zoarces. Similar results 

 were obtained by Punnett (1904) for the viviparous 

 shark, Etmopterus [Spinax] niger. In Salmo, Schmidt 

 (1919c) has lately demonstrated that the finer differences 

 in the number of vertebrae of both parents are inherited, 

 and in the viviparous teleost Lehistes reticulatus, the 

 same author has found (1919a, 1919&) that minor varia- 

 tions in the parental number of dorsal fin-rays are in- 

 herited. In somewhat similar fashion Sumner (1918, 

 etc.) has demonstrated that subspecific differences in 

 color and size in the mouse genus Peromyscus are in- 

 herited, even under changed enviromental conditions. A 

 considerable body of indirect observational evidence^ 

 might be brought forward, if needed, in confirmation of 

 the assumption that these fine racial differences are in- 

 herited. 



Clearly the same sort of variations as are induced by 

 altered environmental conditions do characterize geneti- 

 cally distinct local races of fishes. Furthermore, the^e 

 two sets of correlations display certain striking simi- 

 larities or analogies, the significance of which the writer 

 is attempting to determine in the series of studies of 

 which the one here reported is a part. 



LITERATURE CITED 



Hubbs, Carl L. 



1919. The Nestin<i Hnl.its of Certain 8uiifishes as Obs€rved in a Park 

 Lagoon in Chicago. Afjuutic Life, Vol. i, pp. 143-144. 



