NATURAL SCIENCES OP PHILADELPHIA. 261 



It may be remarked, that the Trachurus boops of Girard is a typical Caranx 

 of Bleeker, and nearly allied to a species previously placed by Girard in a genus 

 called by him " Carangus Girard." Dr. Giinther has called attention to the 

 discrepancy between Girard's diagnosis of Trachurus and that of Trachurus 

 boops. The name of Caranx boops has been given by Cuvier and Valenciennes 

 to a Carangoid, but, as the species belong to different genera, the name of 

 Caranx boops may be retained for the Californian fish. A near ally is the com- 

 mon Caranx chrysos (Dekay) of the Atlantic coast. 



Genus Trachurops Gill. 



Trachurops brachychircs Gill. 



This species is very closely related to the Trachurops crumenophthalmus of 

 the Atlantic, but appears to differ by the less length of the pectoral fins. The 

 description of form, &c. would be equally applicable for the two ; for the pre- 

 sent, therefore, the following formulae for the two specimens in the collection 

 and the annexed table of measurements are deemed sufficient. The tips of 

 the caudal lobes are broken in both specimens. 



D. VII. + I. I. 26. A. II. I. 22. 



Lateral acute plates 36, 37. 



Trachurops differs from Trachurus by the presence of scutellae only on the 

 hinder half of the lateral line. 



Length to end of middle caudal rays (8 l-5th-8,) 100 (-f 14.) Body Greatest 

 height 26-25. Distance of vertical of end of dorsal to end of median caudal 

 rays 16-16. 



Head Greatest length 29-29 J. Distance from snout to end of spine 28-28 J. 

 Width of interorbital area -07. Length of snout 8-8J. Length of opercu- 

 lum .07. 



Orbit Diameter 9-9. 



Dorsal Height of third spine 13-13. Height at longest ray 12-lU. 



Anal Height at longest ray 11^-10. 



Caudal Length of middle rays 7|. Length of external rays 21 -f- 4. 



Pectoral Length 24-24. 



Ventral Length 14-13. 



Genus Decapterus Bleeker. 



The genus Decapterus of Bleeker appears to be a natural and homogeneous 

 one, but at the same time embraces species which differ considerably in denti- 

 tion, and which may consequently be distributed among sections distinguished 

 by such differences. The dentition appears to be constant in the species and 

 to be at least of equal value with that which has induced naturalists to sub- 

 divide the analogous family of Clupeoids. 



The sections known to us are the following: 



Eustomatodos. Teeth on the jaws (uniserial), vomer, palatine bones and 

 tongue. 



Decapterus muroadsi Blkr. D. kurroides Blkr. 



Decapterus verus. Teeth on the jaws (uniserial), vomer and palatine bones, 

 Tongue smooth. 



Decapterus kurra Blkr. 



Gymnepignathus. Teeth on the lower jaw (uniserial), vomer and palatine 

 bones. Tongue and upper jaw smooth. 

 Decapterus macrosoma Blkr. 



Eyepigymnus. Teeth on the lower jaw (uniserial), and tongue. Upper jaw 

 and palate smooth. 



Decapterus hypodus Gill. 



1862.] 



