114 Dr. C. F. Liitken on the Changes of Form in Fishes 



12. Caranx, Carangichthys ; Gallichthys; Selene 

 (Argyeeiosus, Vomer). 



In the Caranx group too many and too few genera have 

 been established. Following the principles adopted bj certain 

 authors, we might establish still more of them 5 for several un- 

 described species represented in our museum must furnish 

 types for new divisions ; on the other hand^ we cannot approve 

 of suppressing them all. A critical revision allows us to 

 retain the six following genera : — 



1. Trachurusj Cuv. (Gthr.). The lateral line is cuirassed 

 throughout its whole length. The species of this genus have 

 erroneously been united into a single one ; I am able to dis- 

 tinguish the following : — T. Linncei, Malm, the form from 

 the Northern seas, which, however, is also met with in the 

 Mediterranean j T. mediterraneus (Steind.), which also pro- 

 bably occurs in the Northern seas, where, however, it is cer- 

 tainly rare ; T. Cuvieri^ Lowe (Madeira, West Indies, west 

 coast of South America) ; T, jcqoonictis, Blkr. (China, Aus- 

 tralia). The relative proportions between the two parts of 

 the lateral line, its more or less sudden or oblique inflexion, 

 and the height of the plates in proportion to their breadth, 

 furnish good specific characters. 



2. Megalaspis, Blkr, With 8-9 finlets separated from the 

 dorsal and anal. 



3. Becapterus^ Blkr. A single finlet (the last ray of the 

 fin) separated from tlie dorsal and anal. 



4. Caranx^ Cuv. Lateral line incompletely cuirassed as in 

 2 and 3 ; no isolated finlets. Carangichthys is only a young 

 Caranx with the prseoperculum denticulated. This genus has 

 been divided into a great number of subgenera, which it would 

 be superfluous to enumerate, and which ought all to be sup- 

 pressed. 



5. Gallichthys J Cuv. Naked, or nearly scaleless ; the first 

 dorsal is rudimentary in young individuals, and altogether 

 wanting in the adults. Blepharis^ Scyrisj Hynnis, &c. are 

 founded upon differences arising from age, and must conse- 

 quently be eliminated. 



6. Selene, lja.c. {Vomer, Argyreiosus, &c.). 



The young of Caranx and Trachurus, down to a length of 

 10-14 millims. for the smallest, are often brought by the sailors 

 and we thus possess a great number of them • but it is not pos- 

 sible to determine their species with exactitude except when 

 they occur in more complete series, which enable us to recognize 

 the characters of the adult. In my memoir I indicate the diffe- 

 rences arising from age that I have observed in certain species 



