KENDALL: NEW ENGLAND SALMONS. 



in another narrowly meet. Brachymystax resembles Coregonus only slightly in the size 

 and shape of the mouth. When the parietal character in each of these genera is consid- 

 ered along with other characters, it is seen, even if they are as stated by Boulenger, that 

 they do not intergrade. If the parietal character alone is considered there is an apparent 

 intergradation, but this disappears when taken in combination. Boulenger (1895, p. 

 300) calls attention to the small mouth (coregonoid) and small scales (salmonoid) of 

 Brachymystax, as evidence of its intermediate position between Coregomis and Salmo. 

 Derivatively it cannot be so regarded. PubUshed descriptions of Brachymystax indicate 

 that the only coregonoid character is that of a small mouth. The other characters are 

 obviously charUke. Its parietals do not meet on the cranial, median line in front of 

 the supraoccipital. In the parietal character and small mouth Thymallus is more closely 

 coregonoid, and in its scales and some other characters more salmonoid. But it does not 

 form a link in any connected chain comprising also Coregonus, Brachymystax, and Salmo, 

 or Salvelinus. The ensemble of characters is more than generically distinct from the 

 coregonids or salmonids, as probably also is that of Stenodus, and doubtless they repre- 

 sent distinct lines of development from ancestral branches of the common salmonoid 

 stock. The respective family characters are those of addition or reduction, as the 

 case may be. 



The present memoir recognizes and defines the following New England salmonoid 

 famihes: all four (Salmonidse, Coregonidse, Argentinidse, and Osmeridae) have a mesop- 

 terogoid. 



TABLE L 

 The Differential Characteristics of the Salmonoid Families. 



'The stomach of Argentina silus is slightly eaecal, that is, somewhat conic posteriorly, not evenly curved as in Salmonida;. 



-This character is negative in all but Osmeridfe, except possibly Argentinidse. 



'Regan failed to recognize the opisthotic in Argentina. It is present, however, but somewhat concealed by the superimposed 

 and overlapping parietals and frontals. 



*Argentina silus has three upturned vestigial or rudimentary vertebrse following the last fully developed one. 



^Since this statement was written it has been found that Weber (1886) says that the intestine of Coregonus oxyrinchus is 

 attached posteriorly to a ventral mesentery. From what he says of C. lavarelm it is inferred that it also was found to have 

 a ventral mesentery. Kendall (1921, p. 197) found none in Coregonits clupeaformis. 



