HORSE-MACKERELS. 



83 



ranx, apijarently ending at the middle of tlu; orbits or 

 over their anterior part, but contiinied more oi- less 

 distinctly l)y the marginal ridge; of the frontal bones. 

 The other, outev latei-al ridge on the skull starts from 

 the OS sqi((iiii<)f!inii (pferoficioit) ;ind is generally con- 

 fined to the posterior frontal bone {os sphenoticum), 

 but sometimes extends to the middle of the orbits. 

 Though these ridges are not \vanting in the true Mac- 

 kerels, they are much less highh' developed and do 

 not extend so tar forward". This difference, however, 

 like the nund)er of the vertebrae, is an internal one 

 and as a character is thus subject to practical difficul- 

 ties in its employment for the determination of species 

 belonging to this famih-. Furthermore, as it is rather 

 a difference in the degree of development than in form*, 

 its validitv as a family character may be doubtful, 

 though we liere retain the Carangoid familv in order 

 particularly to distinguish the Horse-Mackerels in our 



of the frontal bones and even the rostral region-^ These 

 juvenile marks bear ^vitness to the original analogy 

 between this family and the Beryx type, as well as 

 witii tlie ('ottichr, though the Carangidce are untjues- 

 tional)l\- brought nearer to the latter by the compara- 

 tively late appearance of the scales on the body, which 

 in certain forms are completely wanting. The other 

 changes due to age, as we have already seen in the 

 Bramoids, consist in the elongation of the form of 

 the body and of the pectoral fins — the latter becoming 

 more and more pointed and directed more and more 

 upwards with a. more horizontal base — and also in 

 the diminution of the ventral fins. We have also to 

 notice in the Carangidce the reduction of the first dorsal 

 fin and of the spinous ravs in the anal, the changes 

 in the latter causing some likeness to the family of the 

 true Mackerels. In some Carangidce {Selene vomer), as a 

 compensation for this reduction, the anterior parts of 



Fauna as a connecting link between the Bramidfe and the second dorsal and the anal fins are developed into 



the Mackerel gvoup, a position clearly pointed out for j high, falciform flaps and the pectoral fins are simulta- 



them ])y the development of the above-mentioned. Ion- I neously elongated. In others again {Selene setipinnis) 



gitudinal I'idges on the skull. | age also causes a reduction in the length of the anterior 



The correctness of this procedure is also shown parts of the dorsal and anal fins. 



l)y the de\elopmental changes due to age, ^vhich are i In a family -with so great changes of development 



better kno^vn in the CarangidfC than in the Scombrklce. 

 The most detailed information on this point' is given 

 by LuTKEN in his excellent work''. It is a universal 

 rule that in the CarangidtP, as in the ScomhridcB, the 



the definition of the genera and species has naturally 

 been diflScult and unfixed, for the different stages of 

 development, before their correct signification was known, 

 were regarded even as separate genera. However, even 



margin of the preoperculum is furnished with teeth or ' after the corrections made by later writers on this 



spines during youth, there generally being a, iew large point, the Carangoid family still contains a large num- 



spines at the corner and smaller spines or teeth on ber of species. Jordan and Gilbert^ estimate the 



each side of them'. In the Pilot-fish {Naucrates) si- I number as high as 180, the great majority of which 



milar spines appear not only on the preoperculum but belong to the tropic seas of both hemispheres. Many 



also on the posttemporal bone, the supraorbital margin are highly esteemed as an article of food, and as they 



" The difiEerence is given by Gunther, though not as a family chiiracter, and may be found in his descriptions of the skeleton of 

 Scomber scoynbrtts (Cat., 1. c., p. 358) on the one hand, and Garanx trachnriis (Cat., 1. c, p. 421), Chorinemus Itjsan (Cat., 1. c, p. 472) 

 and Lichia glauca (Cat., 1. c, p. 478) on the other. 



' This is also the case in the large species of Tunnies, where these ridges are, it is true, comparatively much lower than in the 

 Carangidce, but still high enough to cause it to be referred to as an exception wlien the supraooipital ridge in Orcymts thynnus (see Cnv., 

 Val., Hist. Nat. Poiss., \'III, p. G6) may be traced as far forward as the ethmoid bone. 



' There are several remarks on tlie subject, however, in Gill: Proc. Acad. Nat. Sc. Philad. 1862, pp. 430 and 440. 



<* Spolia Atlantica, 1. c., pp. 504—552. 



■^ In an Indian species, Caranx (Carangichthys) typus, these teeth are retained even by adult specimens, provided that Bleekeb's de- 

 scription be really based on examination of fnllgrown specimens; and in Caranx Upturns from the West Indies, they occur as uniform teeth 

 at the corner of the preoperculum, though tliey are scarcely visible except on the skeleton. On the removal of the skin both the suboper- 

 culum and intcroperculum also present distinct erenulations at the outer margin. 



f That this genus, too, should be regarded as representing the earlier developmental stages of the family type, appears from its colo- 

 ration, from llic dark transverse bands, the number of which diminishes with age, while in Caratix these bands are generally present, it is 

 true, but only as a juvenile character. Caranx nraspis (Uraspis carangoides), however, according to Bleeker, retains these transverse bands 

 even when fullgrown. 



!' Syn. Fish. N. Amer., Bull. U. S. Kat. Mus., Xo. Il3, p. 431. 



