COLLETTE and RUSSO: SPANISH MACKERELS 



ANTERIOR 

 EPIBRANCHIAL 



POSTERIOR 

 EPIBRANCHIAL 



\ 



COELIACO- 

 MESENTERIC 



a b c 



FIGURE 6. — Anterior arterial system in ventral view. Numbers indicate vertebral centra, stippled areas where pharyngeal 

 muscles originate, a. Scomberomorus multiradiatus , off the Fly River, Gulf of Papua, 272 mm FL. b. Acanthocybium 

 solandn, Revillagigedos Is., 1,068 mm FL. c. Grammatorcynus bilineatus, Timor Sea, 453 mm FL. 



UROGENITAL SYSTEM 



The only reference to the anatomy of the uro- 

 genital system in Scomberomorus (other than 

 fishery biology studies of the gonads) is Kishi- 

 nouye (1923) on Japanese species and Acantho- 

 cybium. The paired gonads lie along the dorsolat- 

 eral body wall and are visible in ventral view in 

 mature adults. The kidney lies dorsal to the layer 

 of fibrous connective tissue which forms the dor- 

 sal wall of the peritoneum. Anteriorly, the kidney 

 divides into a pair of narrow projections which 

 extend along the sides of the parasphenoid and 

 usually reach the posterior end of the "midridge" 

 of the prootic. The anterior ends of the kidney 

 surround the origins of the pharyngeal muscles 

 on the vertebral column and usually separate 

 along the middle of the vertebral column. In the 

 vicinity of the esophagus, the kidney expands 

 laterally and forms two projections which may 

 extend anteriorly to the upper end of the gill slits. 

 Posteriorly, near the posterior fifth of the body 

 cavity, the kidney narrows to an elongate trian- 

 gle (Fig. 8). The branches of the "ureter" (meso- 

 nephric ducts) join to form a common trunk just 

 before entering the urinary bladder. The ureters 

 enter the urinary bladder either at its anterior 

 end or on its dorsal surface. The urinary bladder 

 (Figs. 9, 10) is either ovoid or elongate, depending 

 on degree of inflation, and is located in the 



mesenteries between the gonads in all species 

 except S. sinensis. Scomberomorus sinensis has a 

 specialization of the urinary bladder unique to 

 scombrids and, so far as we know, vertebrates in 

 general. In this species the urinary bladder has 

 become hypertrophied and occupies the space 

 inside the swim bladder (Fig. 5). Acanthocybium 

 (Fig. 2b) has an elongate urinary bladder that 

 extends anteriorly one-third to two-thirds the 

 length of the visceral cavity. 



OLFACTORY ORGAN 



Kishinouye (1923) provided a generalized ac- 

 count of the olfactory organ of several scombrids. 

 More detailed studies have been made on Scom- 

 ber scombrus (Burne 1909), Sarda sarda (Treti- 

 akov 1939), Allothunnus fallai (Nakamura and 

 Mori 1966), Katsuwonus pelamis (Gooding 1963), 

 Thunnus (Iwai and Nakamura 1964a; Gibbs and 

 Collette 1967), and the bonitos, Sardini (Collette 

 and Chao 1975). As in other scombrids, the olfac- 

 tory cavity in Scomberomorus has a small ante- 

 rior naris and a slitlike posterior naris. No infor- 

 mation on the supplementary sacs, or accessory 

 olfactory cavity (Iwai and Nakamura 1964a), was 

 obtained from the present study comparable with 

 that of Tretiakov (1939), who described three 

 supplementary sacs (middle, maxillary, and ros- 

 tral sacs) in Sarda sarda. The central axis of the 



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