Notes on Bonito— Klawe 
491 
Fig. 3. A 42 mm. Sarda chiliensis caught on August 5, 1951, off Baja, California. Drawing by George 
Mattson of the U. S. Bureau of Commercial Fisheries. 
are concentrations of chromatophores in various 
parts of the peritoneum but especially along 
its dorsal portion. A series of chromatophores 
can also be seen along the mid-ventral line 
extending almost to the tip of the urostyle. 
Identification of the two specimens, as to 
which of the two species they represent ( S . 
chiliensis or S. orientalis ) , is impossible with- 
out a complete developmental series. 
Other specimens of Sarda available from the 
eastern Pacific Ocean are several individuals 
over 30 mm. in length caught off Chile and 
Peru and two individuals caught off Baja Cali- 
fornia. On the basis of gill raker counts (see 
next paragraph), all individuals have been 
identified as S. chiliensis. A 43 mm. individual 
caught off Baja California is illustrated in Fig- 
ure 3. The general appearance of these juveniles 
resembles that of Euthynnus sp. However, sep- 
aration between these fishes is possible, as the 
outline of the first dorsal fin is concave in 
Euthynnus and convex in Sarda when the spines 
are erect. Upon closer examination the two 
genera can be separated easily, as the meristic 
counts differ considerably. The densely pig- 
mented pelvic fins shown in Figure 3 are 
characteristic of small Sarda . It is worthwhile 
to mention that the first dorsal fin in small S. 
Fig. 4. A 160 mm. Sarda chiliensis caught on January 3, 1956, off northern Peru. 
