no. 3C47 PERCIFORM FISHES — GOSLINE 37 



provides a source of attachment for the body musculature, which 

 extends anteriorly along either side of it. The interorbital commissure 

 of the lateralis canals is always complete and has a median opening 

 between the frontals on the top of the crest. 



In the scombroid fishes (including the trichiuroids) , the 

 supraoccipital crest and the body musculature do not extend forward 

 over the head medially beyond the supraoccipital, except, to my 

 knowledge, in Gasterochisma, Scomberomorus, and Acanthocybium. 

 Other than in these genera, there is either a median open space 

 between the frontals posteriorly or a transparent area in the frontals 

 directly under which is an expanded "pineal organ" (Rivas, 1953). 

 The interorbital commissure of the lateralis system is never complete 

 (it was not located in the large skull of Gasterochisma examined). 

 Except in Scomberomorus and presumably Acanthocybium, the two 

 lateral portions of the commissure are widely incomplete on the 

 midline; in Scomberomorus and presumably Acanthocybium, the 

 two halves of the commissure extend up the outside surfaces of the 

 halves of the frontal crest and open by separate exits on either side 

 of its rim. If Rivas (1953) is correct in postulating the pineal body as 

 a light receptor in scombroids, then the scombroids, except Scom- 

 beromorus and Acanthocybium, have a rather different system of 

 sensory perception on the top of the head than the carangids, and the 

 two exceptional genera would represent an incomplete return toward 

 the carangid system. 



(2) In the Carangidae, the usual five suborbital bones are present 

 (see Suzuki, 1962), forming a typical complete circumorbital ring. 



In the scombroids, the suborbital bones behind the eye are 

 variously modified or absent. In Scomber and Rastrelliger (Allis, 1903, 

 pi. 3; fig. 4; Starks, 1910), they form a series of flat, somewhat 

 expanded plates that appear to be variable in number. In Scombrola- 

 brax, they occur as rather numerous small ringlike ossicles (see above) . 

 In most of the other scombroids, the posterior suborbitals, along 

 with the postorbital section of the infraorbital canal, are absent or 

 represented by scalelike ossifications. 



(3) In the Carangidae, the vertebrae are almost always 24 and 

 never exceed 26 (Suzuki, 1962). 



In the Scombridae, the vertebrae are 30 or more. 

 To me, a more promising area of scombroid origin among the percoid 

 fishes is that represented today by the Pomatomidae, especially 

 Scombrojps. It is not so much that the pomatomids positively fore- 

 shadow the scombroids as that they appear to be more generalized 

 percoids, lacking the rather numerous nonscombroid specializations 

 found in the Carangidae; e.g., the median frontal crest bearing the 

 interorbital lateral-line commissure. The Pomatomidae have the 



