62 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



on larger juveniles and adults show that they 

 were usually taken from or near the bottom in 

 shallow waters out to depths of about 25 fathoms. 

 We have heard reports of large specimens of 

 Alutera floating at the surface far out at sea, and 

 we have also been told that these and large speci- 

 mens of other filefish genera have been seen by 

 skin divers on or near the bottom. All of the 

 large specimens on which we have adequate 

 collection data were taken by bottom-collection 

 methods. 



We are indebted to the following persons for 

 making specimens available that were instru- 

 mental in this study: James E. Bohlke, Academy 

 of Natural Sciences of Philadelphia; Eugenie 

 Clark, Cape Haze Marine Laboratory; Earl E. 

 Deubler, Jr., University of North Carolina; W. I. 

 Follett, California Academy of Sciences; John D. 

 Kilby, University of Florida; George S. Myers, 

 Stanford University; Leonard P. Schultz, U.S. 

 National Museum; Victor G. Springer, Florida 

 State Board of Conservation; and Royal D. 

 Suttkus, Tulane University. We are grateful 

 for the assistance of the entire staff of the U.S. 

 Bureau of Commercial Fisheries Biological Lab- 

 oratory at Brunswick. 



METHODS 



Body measurements greater than about 6 

 millimeters were taken with dial calipers or with 

 dividers and a metric scale ; smaller measurements 

 were taken with a microscope and calibrated 

 micrometer eyepiece. Measurements of less than 

 100 mm. were generally recorded to the nearest 

 0.1 mm.; larger measurements, to the nearest 

 millimeter. 



Counts of rays of the soft dorsal, anal, and 

 pectoral fins were made with a microscope and 

 transmitted light on all specimens of less than 

 about 250 mm. standard length. Each discernible 

 ray was counted, including the small or rudimen- 

 tary ray that occasionally is present at the 

 posterior end of the fins. Only the pectoral and 

 caudal fins have branched rays. All species 

 examined have two dorsal spines and one pectoral 

 spine; the second dorsal spine and the pectoral 

 spine become minute or vestigial with growth of 

 the fish. The pectoral spine was not included in 

 the count of that fin. By definition, a ray in a 

 fin may be of two types: a spine (which usually 



has a pointed tip, is never segmented, and is never 

 branched) and a soft ray (which usually has 

 blunt or fimbriated tip, is segmented, and may or ^ 

 may not be branched) . 



Obvious deformities were neither counted nor 

 measured. 



The following measurements are illustrated in 

 figures 1 and 2. 



Standard length (S.L.). — Distance from tip of 

 snout (upper lip) to middle of caudal-fin base. 

 The caudal-fin base is distinguished externally as 

 the curved ridge formed by the proximal ends of 

 the caudal -fin rays. This ridge is not to be con- 

 fused with the line formed by the extension of body 

 skin and scales onto the bases of the caudal rays. 

 Percent of standard length is recorded as "% S.L." 



Body depth. — Distance between origins of second 

 dorsal fin and anal fin. 



Head length. — Distance from tip of snout (upper 

 lip) to upper end of gill slit. 



Snout length. — Distance from tip of snout (upper 

 lip) to anterior margin of orbit. 



Eye diameter {orbit diameter) . — Horizontal diam- 

 eter of orbit. 



Eye to dorsal spine. — Straight-line distance from 

 top of orbit to front center of base of first dorsal 

 spine. 



Dorsal-spine length. — Distance from front center 

 of base of dorsal spine to its tip. 



Caudal-Jin length. — Distance from middle of 

 caudal base to tip of longest caudal ray. 



Peduncle depth. — Least depth of caudal pe- 

 duncle, a vertical measurement from posterior end 

 of anal-fin base. 



Peduncle length. — Shortest distance, from poste- 

 rior end of anal-fin base to caudal-fin base along 

 ventral surface of peduncle. 



IDENTIFICATION 



Our dichotomous keys to filefishes of the western 

 North Atlantic have been constructed to allow for 

 intraspecific and interspecific variation, and for 

 ontogenetic changes in form and morphometries. 

 When our series of specimens was small or in- 

 complete in size range, we attempted to anticipate 

 variation and ontogenetic changes, particularly 

 by not using or qualifying the use of characters 

 that we suspect might not be valid at specimen 

 sizes we did not have. 



