440 PROCEEDINGS OP THE ACADEMY OP 



species, as understood from the examination alone of the literature of the 

 science, are indicated in the following synopsis. 



I. Teeth developed. 



a. Spinous dorsal developed Doliodou. 



0. Spinous dorsal replaced by free spines Trachynotus. 



II. Teeth of jaws and pharyngeal hones absent. Dorsal spines 



free Bothroliemus. 



The two species of Doliodon were distinguished by their height and the 

 number of rays, and are really distinct. One of them, however, also appear- 

 ed under two other genera. The differences above signalized are the result of 

 age. 



When extremely young, the preoperculum is armed at the angle with three 

 large spines, and smaller ones above and below. The spinous dorsal is de- 

 veloped as a perfect fin, and teeth are present on the jaws and palatine arch. 

 In this stage the species has never been described by previous naturalists, and 

 consequently has received no name as the corresponding stage of Naucrates*has. 



At an early period, the preopercular spines are absorbed in the substance of 

 the preoperculum and disappear. The spinous dorsal and the teeth are still 

 retained. In this condition it remains for some time ; the spinous dorsal, 

 however, gradually losing its relative size, while the soft vertical fins increase. 

 In this stage the species belongs to the genus Doliodon of Girard.f 



At a later period, the membrane connecting the dorsal spines has become 

 obsolete, and the species then represents the genus Trachynotus as under- 

 stood by Cuvier and Valenciennes and others. 



Finally, in old age the teeth of the jaws, palate and pharyngeal bones have 

 fallen out, and the lobes of the dorsal, anal and caudal fins attained their 

 greatest extension and become pointed. This final stage has been made known 

 by Holbrook under the new generic name of Bothrolaemus. 



The various differences in the development of the soft fins and the den- 

 tition were correctly appreciated by Giinther, and the several names have 

 been referred to the synonymy of the species to which all belong. 



It is a rather singular coincidence that Linnaeus has found the same num- 

 ber of rays in his Gasterosteus saltatrix which is the Pomatomus saltatrix of 

 the present article, as in the G. ovatus, and this identity of the radial formu- 

 la? has induced Schneider to unite the two species which belong to at least 

 different subfamilies. J 



Subfamily CENTRONOTIN^E Gill. 

 Genus NAUCKATES (Raf.) Cuv. 

 Seriola sp. Cuv. et Vol. 

 Nauclerus Cuv. et Vol. 



Nadckates ductor (Raf.) 

 Adult. 

 Gasterosteus ductor Linn. 

 Gasterosteus antecessor, Daldorf. 

 Scomber ductor Block. 



" koelreuteri Block. 

 Ceutronotus conductor Lactphdc. 

 Naucrates fanfarus Raf. 



" ductor Cuv. et Val. 



* The genus Nauclerus corresponding to this stage of Naucrates was proposed by 

 Cuvier, and has been unreservedly adopted by every succeeding naturalist. 



t The corresponding siage of Naucrates has been observed by Cuvier and Valenciennes, 

 and made known under the names of Seriola dussumieri and S. succincta. These species 

 have been adopted by their successors. 



I See Histoire Naturelle des Poissons, lome is. p. 229. 



[Sept, 



