THE LEPTOCEPHALUS OF THE AMERICAN EEL. 
85 
chromatophore extending over three to four somites. At the margin of these larger chromatophores 
there are rarely minute chromatophores. 
The two specimens differ from each other very greatly in the shape of the head, the nostrils, the 
development of the pectoral, and the shape of the body. The fact that the large one has lost its teeth 
and its head has assumed a distinct eel shape, together witli the similarity of the structure of the 
caudal, the unique coloration, and the similarity in the number of myotonies, make it very probable 
that the two specimens are different stages of the same species. 
Leptocephalus diptychus, small specimen. 
Leptocephalus diptychus. 
The two specimens differ as follows: 
a. Body more elongate; pectorals a mere ridge; nostrils remote from each other for a distance nearly equal to 
the diameter of the eye; leptocephalous teeth wanting; lower jaw projecting, its tip rounded and enter- 
ingthe profile; no pigment spots about the head; depth 8.6; head distinctly more than half the depth of 
the body, nearly 11 in the length; eye 7 in head, 1.5 in snout; segments 73 + 43 type 
aa. Body elliptical; pectorals well developed; nostrils not yet separated; leptocephalous teeth; jawsnearly equal; 
a pigment spot near the end of the lower jaw, another within the anterior nares, two succeeding each 
■ other between the lower margin of the pupil and the lower margin of the auditory capsule; depth 6; 
head less than half greatest depth; eye 5 in head; segments 76 + 38 cotype 
