428 Memoir Sears Foundation for Marine Research 



and abdomen and the several short spines on the median line of the back between the 

 occiput and origin of dorsal sufficiently characterize this genus. 



Range. Known from a single species, as herein understood, which ranges from the 

 Guianas to northern Brazil and ascends freshwater streams. 



Pristigaster cayana Cuvier 1829 

 Sardinha d'Agua Doce, Apapa (Brazil) 



Figure 108 



Study Material. None. 



Distinctive Characters. In bodily shape, cayana resembles somewhat Ilisha harroweri, 

 but its chest and abdomen are even more strongly convex, forming a very pronounced 

 arc (see Fig. 108). The shape strikingly resembles that of the freshwater characin, 

 Gasteropelecus, but its pectoral fin is much shorter.^^ The several spines on the median 



Figure 108. Pristigaster cayana, about 1 10 mm TL (caudal damaged). Drawn by Ann S. Green after Compos' 

 P. martii. 



line of the back between the occiput and the dorsal fin separate it from all American 

 species of the family. 



Description. Proportional dimensions in per cent of standard length, and counts, 

 from several published accounts, drawings, and a photograph. 



Body: depth 50-56. 

 Head: length 25—29. 



Scales: 39—42. 

 Ventral scutes : 30-33. 



Gill rakers: on lower limb of first arch, 



20-23. 

 Fin rays: dorsal 13—15; anal 46—55; 



pectoral 1 1 . 



53. Moreover it does not appear to possess the enormous pectoral muscles which enable the characin to buzz its wings 

 during aerial flight. — G. S. Myers. 



