i6o Memoir Sears Foundation for Marine Research 



Development. The smallest specimen, only 14 mm, is very slender, its depth 9.15 

 and the head 4.0 times in SL. In this specimen the mouth is nearly terminal, the lower 

 jaw is very thin, the gape ends under the eye, and the maxillary is imperfectly developed. 

 The convoluted intestine, which is usual in larval herring and herring-like fishes, is 

 externally visible. All fins, however, are sufficiently developed to have at least rudimen- 

 tary rays. The body is pale, no doubt transparent in life, as general pigmentation has 

 not taken place. The juvenile markings consist of dark dots, which, exclusive of a few 

 spots at the nape, are on the lower part of the body; and a few less definite ones are on 

 the side of the head. An elongate median streak extends backward from the isthmus; 

 also there are spots along each side of the ventral edge of the abdomen that become 

 darker and more concentrated along the base of the anal and are reduced to a single 

 row on the midventral line of the caudal peduncle. A row of indefinite dark dots ex- 

 tends along the lateral side of the tail from above the anal base to the caudal base; there 

 are a few more dark dots on the caudal fin. 



The body of a fish 20 mm TL is proportionately much deeper than the 14-mm 

 example, as its depth is contained t^.^ times in SL. The proportion of the head does not 

 differ greatly from either the small or large ones described, being 3.75 in SL. Much 

 progress in the development of the mouth parts has been made, however, for the snout 

 is more pointed and it projects prominently beyond the lower jaw. The maxillary is 

 definitely visible and extends well beyond the posterior margin of the eye, where it 

 ends in a rather blunt point. The intestine is no longer visible externally. Pigmen- 

 tation on the lower part of the body remains about the same as in the smaller ex- 

 ample, but dorsally, especially on the median line of the back and on the head, the 

 dark dots are more numerous. 



The advances in development with growth between 20—30 mm are not great. The 

 increase in proportionate depth has continued, with the depth now 5.0 times in SL. 

 The snout has become more pointed and projects somewhat more strongly, about as in 

 adults. Some of the gill rakers are developed, 10 + 20 having been counted in one spec- 

 imen. Pigmentation has advanced somewhat, as dark dots on the back and on the head 

 have become larger and more numerous. The dark line behind the isthmus has virtually 

 disappeared. The dark spots on the side of the abdomen, along the base of the anal, 

 and on the ventral side of the caudal peduncle have become less distinct. A few elongate 

 dark markings at the base of the outer rays of both lobes of the caudal, already present 

 in the 20-mm specimen, have become more distinct. 



In a fish 40 mm long, the depth is contained 4.5 times in SL, and the head '^^.^ 

 times. The cheek and opercular bones are well outlined. And the maxillary, which 

 now reaches the margin of the opercle, is provided with minute teeth along its free 

 margin. The gill rakers on the first arch are so numerous and close-set that they are 

 difficult to count; about 35-45 seem to be present. Pigmentation continues to advance; 

 the dark dots on the back have become more numerous and those on the lower parts, 

 exclusive of the ones along the anal base and on the peduncle behind the anal, have 

 disappeared. The upper parts of the body are slightly straw-colored and the sides 



