NATURAL SCIENCES OF PHILADELPHIA. 85 



The radial formula is also variable. Small specimens between one and two 

 inches long exhibit the following variations : 



1. D. V. -f I. 26. A. II. + I. 24. 



1. D. VI. + I. 26. A. II. + I. 24. 



2. D. VI. + I. 26. A. II. + I. 23. 



3. D. VI. + 1. 26. A. II. + I. 22. 



1. D. VI. + 1. 25. A. II. + I. 23. 



2. D. VI. + 1. 25. A. II. + I. 22. 

 1. D. VI. + 1. 24. A. II. + I- 21. 

 1. D. VI. + 1. 23. A. II. + I. 21. 



Tbachynotus rhodopus Gill. 

 The greatest height equals a third of the length from the snout to the end 

 of the median caudal rays. The head forms scarcely more than a quarter of 

 the length. The diameter of the eye exceeds a third of the head's length, and 

 is a third greater than the length of the snout. The latter is as high as long, 

 and truncated. The lower jaw is not received within the upper. The spinous 

 dorsal from the third spine arched, and highest at its fifth spine, which equals 

 an eighth of the length. The first two spines are short. The second anal 

 spine equals a tenth of the total length. The median caudal rays form nearly 

 a sixth of the length, and nearly equal two-thirds of the longest ones, or of 

 the head. The pectoral fin is contained about five times and a half in the 

 length. 



D. VI. + I. 20. A. II. + I. 18, 19. 



The color is bluish-silvery ; the spinous portions of the dorsal and anal 

 fins punctulated with black ; the ventrals rose-colored ; the other fins yellow- 

 ish and mostly immaculate. 



Numerous specimens of this species were obtained by Mr. Xantus ; but all 

 of them are young, (between one and two inches long,) and have the three 

 radiating spines, &c, of the preoperculum. It must be remembered that the 

 portion of the description referring to the spinous and soft dorsal and anal 

 fins, is only applicable to the young ; the adult doubtless resembles Trachy- 

 notus Carolinus. * The present species is allied to the latter, but at once 

 distinguished by the small number of dorsal and anal rays. The radial formula 

 equally distinguishes it from all previously known species having the same 

 form. The young of Trachynotus ovatus, Gthr., does not essentially differ in 

 form from the adult. 



Trachyxotus nasutcs Gill. 



The greatest height equals two-fifths of the length from the snout to the 

 end of the median caudal rays. The head forms three-tenths or more of the 

 length ; the snout is produced and subconic, and equals the diameter of the 

 eye, and scarcely less than a tenth of the head's length. The lower jaw is 

 received within the upper. The spinous dorsal is highest at the fifth spine, 

 which equals an eighth of the length, or nearly a third of the height of the 

 body beneath. The second anal spine is as long or longer than the fifth 

 dorsal one. The median caudal rays form an eighth or more of the total 

 length, while the external rays only equal a sixth of the same. The pectoral 

 fin is contained five times and a half in the length. 



D. VI. -f I. 20. A. II. + I. 19. 



The color is silvery ; the spinous portions of the dorsal and anal fins 

 thickly punctulated with black ; the ventrals white. 



This species is very readily distinguished from T. rhodopus by the conoid 



* The descriptions of Trachynotus marginatus, C.V. and T. cayennensis, C. V., must be accepted with 

 similar reserve. The statement of the height of the fins of the two new species here described 

 has been retained in order to show how great is the difference between the young and old. 



1863.] 



