S., long. 99°07' W., near the Galapagos Island. 

 Ege also reported three specimens of C. barbatus 

 from the same station (3558). Morrow (1961: 

 256), on the basis of a partial reexamination of 

 the excepted specimen, stated that, "the Dana spe- 

 cimen of C. macouni does not appear to have been 

 mis-identified." Yet nowhere is this specimen so 

 adequately described, or compared with specimens 

 from the usual range of O. macouni, that it can 

 confidently be considered to be G. macouni, in 

 view of the known occurrence of all other 

 specimens of C. macouni. 



Kegan and Trewavas (1929:32 and 34) stated 

 that in C. sloani Bloch and Schneider and in C. 

 danae Regan and Trewavas the proportion of the 

 eye diameter into the length of the lower jaw is 

 "larger in male than female." We have deter- 

 mined that external morphological sexual di- 

 morphism exists in C. macouni. Of 20 of the 

 larger specimens taken on cruise C6303 (stations 

 84.70, 86.92787.80, 89.90, and 90.110), 8 are fe- 

 males with large, ovarian eggs, ranging from 183- 

 207 mm. SL (mean size 197), and 12 are males, 

 162-202 mm. (mean 177). The males have larger 

 eyes than the females (eye into head 3.3 to 3.8 in 

 the males, 4.0 to 4.6 in the females). One of the 

 most pronounced differences between the sexes is 

 the relative size and shape of the postocular organ. 

 Morrow (1961:273) found that in C. macouni the 



postocular organ was generally elongate and tri- 

 angular; the exposed luminous portion was trian- 

 gular or at least, pointed behind, while in other 

 species of Chm/Iiodus the postocular photophore 

 was round or nearly so. His characterization is 

 descriptive of the postocular organ of male speci- 

 mens of C. macouni, especially of the exposed 

 luminous portion, but in the females the organ is 

 different and more variable than in the males. 

 The organ is always smaller in the adult females. 

 In some females the exposed luminous portion is 

 reduced to a small rounded area, less than one- 

 quarter of the area of that in the adult males; in 

 others it is elongated, probably owing to a dif- 

 ferential contraction following preservation of 

 the surrounding tissue (fig. 17). 



MALACOSTEIDAE 



59. Aristostomias scintilla/as Gilbert. 



Figures 16B and 18. 



60.60, H6204, (1) 56 mm. ; 60.80, C6208, (8) 73-214 mm. ; 

 60.90, C6208, (2) 62-168 mm.; 60.120, H6204, (1) 189 

 mm.; 60.180, H6204, (1) 55.5 mm.; 70.80b, B6203, (4) 

 52-64 mm. ; 70.80-5N, B6203, (6) 55-70 mm. ; 80.90, B6203, 

 (1) 78.5 mm.; 80.90-5N, B6203, (2) 64-67 mm.; 83.77, 

 C6303. (1) 92 mm.; 86.92, C6303, (1) 54 mm.; 88.105a, 

 B6303, (1) 58 mm.; 90.70, C6208, (1) 148 mm.; 90.80, 

 O6208, (1) 51.5 mm. ; 97.40, C6303, (4) 44-140 mm. ; 97.50, 

 B6203, (2) 82-129 mm.; 100.40, H6204, (1) 114 mm.; 

 108.63, C6303, (2) 46-109 mm.; 110.40, H6204, (1) 123 

 mm. ; 120.80, H6204, (1) 101 mm. 



?X2.4 

 l97mm.SL 



?X2 8 



187mm. 



$ X3 

 202mm. 



Figure 17.— Chaiiliodus macouni, postocular organs, showing the typical triangular shape in juveniles and 

 adult males (right) and.the variable and frequently elongated shape in adult females (left and middle). 



PELAGIC FISHES, CALIFORNIA CURRENT AREA 



6S." 



