THE SHORE FISHES OF PERU 31 



behind base of first dorsal, with nearly straight distal margin, the 

 outer margin 2.0 to 2.3 in head; pectoral large, with a slightly concave 

 distal margin, inserted under or more usually somewhat behind third 

 gill slit, its greatest length 5.4 to 6.0 in length anterior to base of 

 upper lobe of caudal. 



Color of adults in alcohol pale gray above, with specks or flecks of 

 white, distinct in some specimens, obscure or wanting in others, 

 probably always present in life; distal margins of dorsal fins dusky, 

 more prominently so in some specimens than in others; distal margins 

 of pectoral and ventral generally paler than rest of fins. Young with 

 dark bars above (especially prominent in seven embryos, all from one 

 female and all around 210 mm. long) ; first two forming a very narrow 

 rectangle between the eyes; next pair also tending to meet at sides 

 to form a broader rectangle at occiput; third pair forming a notably 

 shorter quadrangle just in advance of first dorsal; five or six separate 

 bars extending down to about middle of side under and posterior to 

 first dorsal, and one or two dark spots on caudal peduncle. Some of 

 the bars and the spots on the posterior part of the back have disap- 

 peared with age or faded in preservative, and the others are less distinct 

 in a specimen 295 mm. long. 



As no specimens between a length of 295 and 555 mm. are available, 

 the length or size at w^hich the bars disappear cannot now be stated. 

 It is certain, however, that they are lost with age, as Mr. Lobell of 

 the Mission stated in his field notes, "The adult did not have the 

 black markings of the embryos, but rather several rows of white spots 

 on the side on a brown ground." 



The description is based principally on six specimens, 555 to 700 

 mm. long. The embryos, already mentioned, and a paratype of M. 

 abbotti, 295 mm. long, differ in addition to the dissimilarity in color 

 already described, in having a slenderer body, the depth at the ori- 

 gin of the first dorsal being contained 9.0 to 10.0 times in the length 

 to base of upper lobe of caudal, and the eye is larger, 5.7 to 7.0 in 

 head. In the embryos the teeth are virtually undeveloped. The 

 type of M. abbotti, which now is 530 mm. long, agrees well with the 

 larger specimens in the present collection, though the origin of the 

 first dorsal and that of the anal are somewhat farther forward. It 

 is evident from the specimens at hand, and from descriptions that 

 considerable variation as to the position of the fins occurs. 



It is virtually impossible to distinguish this species and AI. dorsalis 

 from the original description, which is inadequate. It is partly for 

 that reason that Garman (1913, p. 178) considered it identical with 

 M. dorsalis and that Evermann and Radcliffe (1917, p. 6), although 

 recognizing M. mento as distinct from M. dorsalis, considered the 

 specimens before them as undescribed, giving them the name M. 

 abbotti. However, Bigelow and Schroeder (1940, p. 429) came to the 



