THE SHORE FISHES OF PERU 29 



dd. First dorsal placed more anteriorly, the midpoint of its base being nearer 

 insertion of pectorals than ventrals; teeth of upper jaw at least 



serrate Eulamia (p. 37) 



cc. Labial folds well developed, present on both jaws; teeth not serrate. 



Scoliodon (p. 40) 

 bb. Spiracles present. 



e. Teeth large in both jaws, lateral ones curved backward, coarsely serrate 

 along both margins; snout and mouth very broad; young at least with 



dark spots or bars Galeocerdo (p. 41) 



ee. Teeth smaller, usually with median nonserrated cusps, more or less 

 notched or serrate at base; snout and mouth rather narrow; color 

 plain Galeorhinus (p. 42) 



Genus MUSTELUS Link, 1790 



Body moderately robust anteriorly, becoming very slender posteri- 

 orly; head and snout depressed; caudal peduncle slightly compressed; 

 snout more or less produced, rounded; eye lateral, with a well-developed 

 nictitating fold; spiracles small, an oval or elongate slit just behind 

 eye; nostrils large, far apart; mouth crescent-shaped, with well-de- 

 veloped labial folds; teeth low, with broadly rounded margins or with 

 low cusps; dorsal fins similar in shape, the first not far behind pectorals, 

 the second smaller and in part over the still smaller anal; lower lobe 

 of caudal long, without a prominent angle. 



The teeth have often been described as being arranged like bricks 

 in a pavement. That in general is true. However, the teeth indi- 

 vidually have cutting edges, whether provided with cusps or not, and 

 seem to be used for cutting, rather than for crushing. 



KEY TO THE SPECIES 



a. Teeth with nearly smooth rounded margins; young anteriorly with black 

 cross bars above, posteriorly with black spots; adults with small white 



spots or flecks raento (p. 29) 



aa. Teeth anteriorly with a moderately prominent median cusp, lateral ones 

 broader and occasionally with a slight notch; color plain gray at all 



ages dorsalis (p. 32) 



aaa. Teeth anteriorly with a single prominent cusp, most of lateral ones with a 

 small cusp posterior to the large one, with a rather sharp notch between 

 cusps; young with irregular black spots; adults plain gray. 



maculatus (p. 34) 



MUSTELUS MENTO Cope 



Figure 5 



Mustelus mento Cope, 1877, p. 31, "Pacific Ocean at Pacasmayo, Peru" (original 

 description).- — Fowler, 1908, p. 57, fig. 1 (redescription of type); 1940a, p. 

 173, figs. 10-13 (description; compared with dorsaiis and edulis, both recog- 

 nized as distinct); 1941a, p. 222 (references). — Evermann and Radcliffe, 

 1917, p. 6 (references). 



Mustelus edulis P:^rez Canto, 1886, p. 1006, Valparaiso, Chile (original descrip- 

 tion) . 



Galeus dorsalis Abbott (not of Gill), 1899, p. 327, Callao, Peru. 



Mustelus abbotti Evermann and Radcliffe, 1917, p. 6, pi. 1, fig. 2, LaVentanilla 

 and Lobos de Tierra, Peru (original description). — Nichols and Murphy, 

 1922, p. 504, Callao market, Peru. 



