82 BULLETIN 189, UNITED STATES NATIONAL MUSEUM 



a ventral fin during life, only a scar at the point of insertion remaining. 



This species was not recorded previously from Peru or apparently 



from Ecuador. However, a specimen (U.S.N.M. No. 94013) 85 mm. 



long, from La Plata Island, Ecuador, was collected by W. L. Schmitt, 



and the species has been recorded from the Galdpagos Islands. Several 



specimens from those islands and Panama Bay were compared with 



the ones from Peru and Ecuador. The specimens from the southern 



areas agree admirably and differ only slightly from specimens from 



Panama Bay in having a somewhat more projecting mandible and 



rather shorter pectoral fins. However, the Panama material, too, 



varies somewhat in these respects. 



Range. — Mexico (at least as far north as Guaymas, whence I 



have seen specimens) south to Peru (Sechura Bay), and the Galapagos 



Islands. 



Genus ETHMIDIUM Thompson, 1916 



Body elongate, rather strongly compressed; midline of abdomen 

 sharply compressed, with moderately strong scutes; back in advance 

 of dorsal also with a row of scutes on midline; mouth rather large; 

 maxillary about half width of eye, reaching approximately to vertical 

 from posterior margin of eye; upper jaw with a definite notch; teeth 

 absent; gill rakers numerous, those of upper limb extending down- 

 ward and forward across those of lower limb ; no dermal flap on shoulder 

 girdle; scales regularly placed, with vertical radii, about 50 to 55 in 

 lateral series; vertebrae about 48; dorsal more or less over middle of 

 body, with about 16 to 20 rays; anal with rather fewer rays, the last 

 ray slightly enlarged ; ventral with 7 rays. 



Some writers have referred the species of this genus to Potamalosa 

 Ogilby, based on an Australian fresh-water herring. That the South 

 American forms differ generically in several respects was adequately 

 pointed out by Thompson (1916, p. 458), the chief differences consist- 

 ing in the much more numerous gill rakers of the latter, the presence 

 of a notch in its upper jaw, its wider maxillary, the absence of teeth, 

 and in the position of the ventral fins, which are inserted under the 

 base of the dorsal in Ethmidium instead of in advance of dorsal as 

 in Potamalosa. 



A single species is represented among the specimens from Peru now 

 at hand, which differ somewhat from specimens from Chile, as pointed 

 out subsequently. 



ETHMIDIUM CHILCAE, new species 



Machete 

 Figure 17 



Clupea maculata Gunther, 1868, p. 443, Chile, Peru (in part not of Cuvier and 

 Valenciennes; description based on a Peruvian specimen). 



Potamalosa notacanthoides Abbott, 1899, p. 333, Callao, Peru (not of Steindachner; 

 note on type specimens of Clupea notacanthus Giinther; description). — 

 Starks, 1906, p. 778, Callao, Peru (not of Steindachner). — Evermann and 



