3S 



THE AMERICAN NATURALIST [Vol. XLVI1 



jps of Similar Distributional i 



. neglecta 

 . plankionis 



By referring to the key (p. 35) it will be seen that 

 8. enflata is separable from S. neglecta only by the fact 

 that the former occurs in large numbers while the latter 

 occurs in small numbers. These two species then consti- 

 tute Group 1 of similar distributional species, but, while 

 S. enflata falls in Group 1 of similar morphological 

 species, S. neglecta is found in Group 2. It will therefore 

 be worth while to see just how extensively the one species 

 is morphologically differentiated from the other. To this 

 end I have arranged, in the following table, some of the 

 most striking differences between the two species. 



TABLK VIII 



Length of anterior fin. 

 fin. 



Extent of posterior 



ventral ganglic 

 Extends to the 

 ganglion. 



Per 



