Noncompact Groups in Classifying Hadrons

We show that the noncompact groups $U(6, 6)$, $GL(6, C)$, and $U\left(6\right)\mathrm{}\times U\left(6\right)\mathrm{}\times O(3, 1)$ proposed by many authors to underlie a classification of hadrons can be excluded on the basis of existing information on the hadron spectrum. A scheme which at least avoid the obvious difficulties of the above noncompact groups is mentioned.