MNHN A. 6862, considered as the holotype by 

 Bauchot and Blanc (1961, p. 377) and Blanc and 

 Bauchot (1964, p. 456) is, therefore, not a type 

 (Collette, 1966). 



Orcynus pacificus Cooper, 1863. No type speci- 

 men, although mention is made of "State collection, 

 species 1033." 



Gcrmo gcrmon steadi Whitley, 1933. Holotype 

 Australian Museum, Sydney, lA 2457, New South 

 Wales, a misshapen skin, 960 mm. FL, preserved in 

 "formalin with most of the fins broken. Pectoral fin 

 about 45 percent of fork length. Figured by 

 Whitley (1933, pi. xi, fig. 1). 



Characters 



Pectoral fin very long, usually reaching nearly or 

 quite to second dorsal finlct, usually 31 percent of 

 fork length or longer (similar to T. obcsus). Body 

 depth greatest near dorsal and anal origins. A nar- 

 row white posterior margin on caudal fin. Anal 

 finlets silvery or dusky. 



Gill rakers 25-31 (similar to T. obesus and T. 

 albacares). 



Liver with striations on ventral siu'face, its three 

 lobes subequal in length, vascular cones present on 

 its dorsal side (as in T. thynnus, T. maccoyii, and T. 

 obesus). Spleen located on left side, stomach on 

 right. Straight intestine short, the first loop located 

 at about half to two-thirds »the distance between 

 middle liver lobe and anus. Gall bladder exposed in 

 ventral view along right side of straight intestine. 

 Connective tissue on dorsal wall of body cavity much 

 thickened posteriorly. Kidney short, without pos- 

 terior "tail," reaching level of vertebrae 7-9. 



Cutaneous arteries usually originating at level of 

 vertebra 3-4, passing laterally between ribs 3 and 4. 

 and branching between intermuscular bones 4 and 5 

 (as in T. Ihy units and T. maccoyii) ; no posterior com- 

 missure. A single row of arterioles and venules 

 arising from each main lateral cutaneous branch (as 

 in T. albacares, T. tonggol, and T. atlanticus) but 

 from vertebral side of vessels. Post-cardinal vein 

 absent (as in T. thynnus and T. maccoyii). 



Posterior parasphenoid margin forming an acute 

 angle (not as extreme as in large T. thynn us but more 

 acute than in large T. obesus). Supraoccipital crest 

 relatively slender and long, reaching at least to 

 centrum of vertebra 3. 



Anterior articulating (sphenotic) head of hyoman- 

 dibula relatively long and narrow, proportion of 

 length to least width 1.7-2.7. Metapterygoid rela- 



tively narrow, proportion of length of anteroventral 

 margin to postero ventral margin 1.1-1.8. Quadrate 

 relatively narrow, proportion of length to width of 

 horizontal dorsal edge 2.1-2.7. 



Vertebrae 18-(-21 (as in all Thunnus except T. 

 atlanticus). First ventrally directed parapophysis on 

 vertebra 9 (as in all except T. thynnus and T. tonggol), 

 appearing twisted and not extending strongly ven- 

 trad. First closed haemal arch on vertebra 10 (as 

 in T. thynnus, T. maccoyii, and occasionally in other 

 species), forming an angle of 45 degrees or less with 

 the vertebral axis. All haemal prezygapophyses 

 arising from centra, not from haemal arches. All 

 haemal postzygapophyses less than one-fourth cen- 

 trum length. Anteriormost ventrolateral foramina 

 small, their width not greater than basal width of 

 haemal spine. Least height of centrum of 36th 

 vertebra 1.1-1.7, usually 1.4-1.6, in centrum length 

 (similar to T. albacai'cs), centrum commonly taper- 

 ing, with least depth at anterior end (in the other 

 species the vertebra is of nearly equal height 

 throughout). Haemal spine of first caudal vertebra 

 flattened, wing-like. 



Nominal Species 



Although no one seems to have reported any im- 

 portant differences l)etween Atlantic and Pacific 

 populations of T. alalunga, at least since Jordan and 

 Evermann (1926), many recent authors still refer to 

 the Pacific populations as T. gcrmo. Even Jordan 

 and Evermann (1926) admitted that the slight 

 diffei'cnces they noted in body proportions and 

 coloration would probably not be valid when more 

 specimens were examined. Our data on T. alalunga 

 confirm the view that the Atlantic and Pacific popu- 

 lations belong to the same species. Godsil (1948) 

 and Kurogane and Hiyama (1958a, 1959) found 

 slight population differences within the Pacific, but 

 intermingling of a significant portion of the eastern 

 and western Pacific populations of T. alalunga was 

 indicated by tag returns reported by Ganssle and 

 Clemens (1953) and Blunt (1954), and demonstrated 

 by more recent works, including those of Otsu (1960), 

 McGray, Graham, and Otsu (1961), Clemens (1961, 

 1963) and Otsu and Uchida (1963). 



Range 



In the western Atlantic, T. alalunga is known from 

 south of New England to southern Brazil. Squire 

 (1963) presented seven records north of 40° N., the 

 most northerly 42°18' N., 64°02' W. Le Danois 



ANATOMY AND SYSTEM.^TICS OF TUNAS 



101 



