GREAT LAKES COREGONIDS 



321 



Color 



Color, which in most groups of fishes serves as a character to separate even 

 closely related species, is of little value in distinguishing between the species of 

 coregonids in the Great Lakes. While faint color may be present in living fish, the 

 fish die very soon after capture (in fact, the deep-water forms are dying when lifted 

 from the nets), and after death the color fades very soon, leaving a nearly uniform 

 silvery appearance to all the forms. In life Leucichthys and Coregonus are tinted with 

 a green or blue-green, the intensity of the coloration varying with the species. It 

 is deepest in the artedi, especially the manitoulinus form, and usually in nigripinnis, 

 and in these forms (particularly the first two) may often become intensified for a 

 short time after death. In life Prosopium differs strikingly from the rest in colora- 

 tion. The blue-green of the others is replaced in quadrilaterale by a greenish bronze, 

 and the sides have a decided pinkish cast. 



Pigmentation also varies, and usually directly with color — that is, the fish with 

 most intense colors usually have more pigment on the head, especially the anterior 

 parts, and on the body and fins. Manitoulinus and most of the forms of nigripinnis 

 are much more pigmented than any of the other forms. 



The degree of pigmentation varies among the forms of a species. In zenithicus 

 the Nipigon race is much paler and that of Michigan and Huron somewhat paler 

 than the typical race; in reighardi the Nipigon race is much paler throughout than 

 the typical Michigan form, while the forms of Superior and Ontario are somewhat 

 less pigmented; the nigripinnis of Superior is paler than that of the other lakes; the 

 Tciyi of Ontario appears to be a trifle more pigmented than the races of the other 

 lakes; the hoyi of Superior shows a little more pigment on the fins than the forms of 

 the other lakes; the typical artedi form is darker than the albus form of Leucichthys 

 artedi, and the manitoulinus form is darkest of all; the Lake Erie clupeaformis seems 

 to be the palest of the races of Coregonus. 



Vertebrae 



The number of vertebrae in the vertebral column is given for a few individuals 

 of each species, chiefly from Lake Huron. 



Species 



Number 

 of speci- 

 mens 

 counted 



Number 

 of verte- 

 brae 



Species 



Number 

 of speci- 

 mens 

 counted 



Number 

 of verte- 

 bra; 



Leucichthys: 



johannse 



11 



12 

 8 

 6 

 8 



10 



57-60 

 57-59 

 55-58 



57- 59 



58- 60 

 57-59 



Leucichthys— Continued. 



hoyi .. 



17 

 9 

 2 

 8 



12 



55-60 



57- 60 



58- 60 

 60-63 



59- 63 



alpense 



artedi 



zenithicus _ 



nipigon ! 



reighardi >_. 



Coregonus clupeaformis 



nigripinnis 



Prosopium quadrilaterale... 



kiyi 





1 Lake Michigan specimens. ! Lake Nipigon specimens. 



It appears that the number of vertebrae varies for each species and that, on 

 the average, Leucichthys has a lower number than Coregonus or Prosopium. 



