and western North Atlantic are presented by Robins 

 (1974) (Table 1). The first dorsal fin originates over 

 the posterior margin of the preopercle (first predorsal 

 length 22-25) and extends nearly to the origin of the 

 second dorsal (base of first dorsal 55-58). From a 

 rounded anterior lobe (anterior height 14-23), 

 somewhat higher than the depth of the body below it, 

 the height of this fin diminishes, first rapidly and then 

 more gradually (25th spine 4.0-6.2), until the last few 

 rays are hidden in the dorsal groove. The first anal fin 

 is somewhat similar, but lower and much shorter 

 (anterior height 12-16, base 14-17). It originates 57-62 

 (first preanal length) behind the tip of the lower jaw, 

 and 3.7-5.2 behind the vent. After the anterior lobe, 

 which is usually broadly rounded, the height 

 decreases rapidly, then more gradually, until the last 

 rays are hidden in the ventral groove. The second dor- 

 sal and second anal fins are very similar, and are 

 located nearly opposite each other (second predorsal 

 length 77-83; second preanal length 75-81) close 

 behind the first dorsal and first anal fins. They are 

 small (anterior height D 2 - 3.1-4.7; A, - 2.8-3.9; length 

 of base: D 2 - 3.6-4.6; A 2 - 4.0-4.9; length of last ray: D 2 - 

 4.2-7.2; A 2 - 4.8-6.7), with short slightly convex 

 leading edges and long deeply concave trailing edges, 

 terminating in long points. The ultimate rays are 

 broad and flattened proximally and adhere closely to 

 the body of the fish. 



The pectoral fin is moderately long (19-27), and its 

 tip is usually rounded. Its origin is just behind the 

 opercle (prepectoral length 25-27) and low on the side 

 of the fish (distance from orig. D, to orig. P[ 12-14). 

 About eight of the lowest rays are very short, forming 

 a subbrachial dilatation. 



The pelvic fins, which also originate near the oper- 

 cle (prepelvic length 26-29), are somewhat shorter 

 (length 14-22) and are so narrow that their area is 

 negligible, and they appear to consist of a single spine. 

 Poey (1861, pi. 16, figs. 4 and 5; the explanation of the 

 plate [p. 241] mistakenly refers to these figures as of 

 the pectoral) describes the structure of this fin in 

 detail. 



The color of the white marlin has been described by 

 Poey (1861), Goode (1881), LaMonte (1955), and 

 Nakamura et al. (1968). The back and the top of the 

 head are described as dusky blue, and the back also as 

 brilliant greenish blue, darker above (LaMonte, 

 1955). The underparts are silvery white. The transi- 

 tion from the dark dorsal to the white ventral areas is 

 gradual, passing through lines of rich purplish brown 

 and smokey grey (Goode, 1881). The sides are crossed 

 by vertical light blue or light lavender bars (LaMonte, 

 1955). The cheeks and opercles are dusky, with a pear- 

 ly sheen. The membrane of the first dorsal fin is deep 

 blue or bluish purple, with circular dusky spots near 

 its base. The rays are dark blue or black. The first 

 anal fin is dark blue or bluish purple distally, and 

 pearly white proximally. The second dorsal is a deep 



blue, and the second anal is somewhat lighter blue. 

 Outer surfaces of the pectorals are dusky with a 

 pearly sheen, and the inner surfaces bluish purple. 

 The pelvics are blue black. The caudal is dusky blu- 

 ish or brownish, sometimes with pearly reflections 

 in the lower lobe, and the caudal keels are bluish 

 black. 



The colors change in response to the state of excite- 

 ment of the fish. Jaen (1964) states that when a 

 billfish following a bait is pale green, it probably will 

 not strike, but if it is dark-colored and its fins are 

 shiny bright blue, it will strike immediately. The pec- 

 toral fins of the white marlin "light up" especially 

 brilliantly in these circumstances. 



The lateral line of the white marlin is simple and 

 more conspicuous than those of other Atlantic 

 istiophorids. The lateral line originates at the top of 

 the opercular aperture, whence it runs longitudinally 

 for a short distance, then curves away from the back 

 and reaches the median line of the fish near the tip of 

 the pectoral. The lateral line was described in some 

 detail by Poey (1861) and Talbot and Penrith (1963), 

 but LaMonte (1958a) has made the most detailed 

 study of the lateral line, scales, and skin of the white 

 marlin now available. The lateral line is 4 mm wide 

 (6-8 mm, according to Talbot and Penrith, 1963). 

 Specialized subcutaneous overlapping lateral line 

 scales have a complicated system of holes and ducts 

 leading through holes in the surface of the skin to the 

 exterior. These scales roof a relatively wide con- 

 tinuous tube (Talbot and Penrith, 1963). Nonspecial- 

 ized subcutaneous scales are thorn shaped, regular, 

 and only occasionally and slightly overlapping. They 

 show very clearly externally, but are completely con- 

 tained in fibrous integument, and also completely 

 covered by the outer skin of the fish. The surface 

 scales are very small and delicate, with round, radial- 

 ly marked bases and glassy perpendicular spines. 

 There are small round openings through the skin un- 

 der many of these scales. A histological description of 

 marlin skin by Rasquin is included in LaMonte 

 (1958a). 



The gills include four double arches and an acces- 

 sory, reticulated as in swordfish (Poey, 1861). LaMonte 

 (1958b) states, for billfish in general "The wide 

 laminated gills are paired; each pair is connected from 

 the base to within a short distance of the free margins, 

 as if woven together. Gill-rakers are absent or 

 vestigial. This gill structure is typical of the group." 

 We have not found gill rakers on any of the white 

 marlin which we have examined. 



Poey (1861), LaMonte (1958b), and Nakamura et 

 al. (1968) discuss the dentition of white marlin briefly. 

 The dentition is weak, consisting of small patches of 

 denticles or villiform teeth on the jaws, palatines, 

 palatine membrane, and pharyngeals. Poey also men- 

 tions anteriorly directed denticles on the sides of the 

 bill. 



60 



