34 OSTEOLOGY OP SCOMBROlD FISHES 



6 inches long it is just beginning. In a specimen of S. oerstedii, 18 

 inches long, the swelling is exceedingly large, in two 8 inches long it is 

 well developed, and in one 7 inches long it is not yet evident. 



In the skeleton of S. vomer the lower parts of the clavicle and 

 hypocoracoid are slightly thickened, and the lower end of the post- 

 clavicle is swollen club-shaped. In 8. oerstedii some of the interspinous 

 bones are very slightly swollen. 



In Vomer setipinnis, 13 y 2 inches long, there is no occipital swell- 

 ing whatever. Fourteen alcoholic specimens of this species and of 

 V. spixii, from 6 to 12 inches in length, were examined, and they all 

 agree with the skeleton in this respect. In the skeleton the lower part 

 of the hypocoracoids are very much thickened and some of the inter- 

 spinous rays slightly so. 



In a specimen of Citula dorsalis, 11 inches in length, there is an 

 abrupt swelling at the upper angle of the supraoccipital crest, so 

 abrupt as to be almost circular in transverse section; it is % of an 

 inch long and !/4 of an inch deep. It is not dense and ivory-like on 

 the surface, as is usual in other forms, but more spongy and cellular. 

 Just behind it the first interneural is swollen to a similar knob, though 

 not so wide. For the occipital swelling several alcoholic specimens 

 were examined. In two specimens, 23 and 11 inches in length, the 

 swelling is as described for the skeleton. In one, 11 inches in length, it 

 covers the same area but is not swollen over half as full, and in one, 10 

 inches in length, there is no trace of any swelling. 



In Alectis ciliaris, 14 inches long, only some of the interspinous 

 bones are slightly thickened. Four alcoholics, 8 to 10 inches in length, 

 were examined for an occipital crest swelling, but none was found. 



In Trachinotus this bone thickening is more marked than in any 

 other form. In the young of T. Carolines, 1 inches long (with 4 dupli- 

 cate skulls), the bones are all normal. In the adult of T. kennedyi, 

 24 inches in length, and the skull of an unknown species, the cranium 4 

 inches in length, the nasals are much swollen. Each is shaped like an 

 inverted comma (') or like a chemist's glass still. The lower ball-like 

 part is in contact with its opposite fellow, and the arm runs upward 

 and outward to attach it to the cranium. In the largest specimen the 

 ball is ^2 an i ncn across. The preorbital is a heavy dense bone % of 

 an inch thick. The first interneural (or possibly several anchylosed 

 ones) is a large oblong mass of bone slightly overlying the supraoccipi- 

 tal crest, and from its posterior end a ray of bone projects down to the 

 first neural spine. This bone in the large specimen is 2*4 inches long, 

 !/2 an inch deep and % of an inch wide. Between it and the spinous 



