152 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



standard length in specimens between 10 and 20 

 mm., but decreases in specimens between 20 and 

 40 mm . , after which it approximates the standard 

 length rate (fig. 35). 



DIVERGENCE IN MEASUREMENTS OF BODY 

 PARTS FOR UNIDENTIFIED SPECIES 



The length of the snout shows the greatest 

 divergence, which is evident at a smaller size than 

 are other divergent characters. Since the snout 

 length is reflected in the standard length, several 

 graphs were constructed using "standard length 

 minus snout length" as a base for comparison. 

 The "weight" of snout length was thus removed 

 from the base, and comparison of fish with similar 

 body lengths was possible. The divergence in 

 snout length (fig. 36), length of lower jaw (fig. 37), 

 and snout extension (fig. 38), is more clearly 

 defined than in plots against standard length 

 (figs. 29, 30, and 31). When the eye diameter is 

 plotted against snout length, the result is sub- 

 stantially the same: divergence first evident at a 

 standard length of approximately 10 mm. (fig. 39). 



Measurements of head depth, head width, aiul 

 eye diameter, when plotted against "standard 

 length minus snout length," revealed no marked 

 divergence, at least below 20 mm. Values for the 

 unidentified species plot either just above or 

 among the higher values for the sailfish (also 

 noticed in the plots of these values against stand- 

 ard length, figs. 28, 27, and 32). 



Fk:t"Re21. — Sailfish, juvenile 437 iiiilliineters long, "20 

 inches total length, 437 mm. standard length; taken 3 

 miles off Aransas Pass, Texas, Aug. 31, 1941, by Aubrey 

 Xelson " (Photograph courtesy of William Beebe.) 



J<^ 



FiQiRE 22. — General shape and proportions of adult sailfish. 



