PROTECTION OF FEESH- WATER MUSSELS. 17 



4. To insure the least trouble of enforcement of the law, it is neces- 

 sary^ that a minimum size be set, below which no shells of any species 

 may be retained. There are many different species of commercial 

 mussels, and some of them so intergrade as to make exact determina- 

 tion a nice matter in some cases. Distinct size limits for the differ- 

 ent species would introduce peculiar difficulties into the practical 

 workings of enforcement; it would be more troublesome to the sheller 

 to observe the law voluntarily, and loopholes for evasion would more 

 easily be found by the offender of wrong intent. 



Should conditions in certain States or streams subsequently require 

 a higher limit for particular kinds of shells, a supplemental limit 

 may be fixed for designated species; but this could be done without 

 affecting the application of a 2-inch limit as an absolute or universal 

 limit below which no shells of any species could be lawfully taken. 

 It is desirable that few different limits should ever be used, and it 

 seems expedient to have but one size limit until the first legislation 

 shall have been tried out. 



DETAILS ESSENTIAL TO EFFECTI^^E LEGISLATION. 



In concluding this section emphasis may be laid on the value of 

 certain details of legislation. 



AllowoJble margin of undersized shells. — Wliile it may seem desir- 

 able that no undersized shell at any time should be taken away, never- 

 theless it is necessary to make allowance for a margin of unintentional 

 error. Only if the shellers and buyers were to apply an instrument 

 of measure to each individual shell would all possibility of error be 

 eliminated. The sheller will naturally, after a few measurements, 

 come to judge by the eye, and it is desirable that the law should be 

 somewhat liberal, rather than too stringent in the allowance for 

 mistakes. There should, accordingly, be a supplemental provision 

 that if not more than 5 per cent of the shells by number (not by 

 weight) of any bushel are found to be below the size limit, the law 

 shall not be presumed to be violated. 



Illegal possession.— To be practicable of enforcement, the law 

 should be so worded as to make it illegal not only to bring ashore or 

 to offer for sale, but also to have in possession, fresh-water mussels 

 or clams of a size less than 2 inches in greatest dimension. This one 

 provision will obviate much unnecessary expense, as well as undesir- 

 able complications in the detection of violations and the prosecution 

 of offenders. Furthermore, since buyers of the shells would be 

 equally liable to prosecution, the effect would be to destroy the mar- 

 ket for undersized shells, and thus in the most effective way to re- 

 strain the shellers from taking them. 



Method of measuring mussels.— It will be noted that the method of 

 measure is stated as " in greatest dimension," with a view to elimi- 



4789°— 14 32 



