COPEIA 27 



As the worker becomes familiar with the denticles 

 of various species he Will find the habit of briefly- 

 examining those of new material an important aid in 

 his cursory search for clews as to the identity of the 

 species. Only a few days ago a section of a shark, 

 including that part of the body between the origin 

 of the first dorsal and base of the ventral fins, was 

 received and identified at once by this character. 

 Without this knowledge identification would have been 

 difficult and it oftentimes will prove so. In fact this 

 point must be emphasized that these are not an open 

 sesame by which all sharks may be readily identified, 

 but that in a troublesome group they are an aid. In 

 addition the material is easily obtained and retained 

 in permanent form for comparative purposes. 



All who have made a study of sharks know the 

 important diagnostic value of the teeth. Considering 

 the ease with which the jaws may be removed and 

 preserved, the dearth of such material in collections is 

 surprising. While there is some range of variation in 

 the number of rows of teeth, there is a marked con- 

 stancy of form in a given species. 



In large measure the practice of fishermen is to 

 fish intensively for the more important forms and 

 allow the unimportant ones to live and multiply, often 

 at the expense of the more valuable species. If prac- 

 tical uses can be developed for those that are especially 

 destructive to the important forms our gain may be 

 twofold. Many are familiar with the grayfish cam- 

 paign inaugurated last year by the Bureau of Fisheries, 

 and that this fish is being canned on both coasts. The 

 demand is at least ten times the pack and the eggs as 

 well as the livers are by-products of value. 



Owing to the scarcity of leathers the time seemed 

 opportune to interest tanners in the utilization of fish 

 skins. Over 225 shark hides and about 50 skins of 

 other fishes, including cod, hake, grouper, garfish and 

 rays, have been distributed among about 25 tanners 

 for experimentation and a few very creditable samples 

 of the finished product have been received. 



The utilization of this product is not a new idea 

 as many have experimented with it almost universally 

 without success. Lack of success is due to the fact that 

 fish skins have to be processed in a special manner in 

 order that they may be tanned into acceptable grades 



