THE LEPTOCEPHALUS OF THE AMERICAN EEL AND OTHER AMERICAN 
LEPTOCEPHALI. 
By CARL H. EIGENMANN and CLARENCE HAMILTON KENNEDY. 
It is an anachronism to describe “species” of Leptocephali , since Gill, Delage, 
Gilbert, and Grassi have definitely traced various “species” to their adult forms. 
Nevertheless this is what we have done. Our excuse is that with but two exceptions 
we have not been able to connect any of the forms examined with their adult stage. 
It may take many years to complete the series demonstrating the life history to which 
each of the species described belongs, and in the meanwhile it will be advantageous 
to have definite forms placed on record for the benefit of all who may secure Lepto- 
cephali and may not be within reach of the specimens examined. 
In preparing this account we have found Stromman’s “ Leptocephalids in the 
University Museum at Upsala” of great value. It is unfortunate that Stromman 
neglected to count the segments, since Grassi has demonstrated that this is one of 
the characters in which a Leptocephalus agrees with its adult form. 
Several of the species to be described here are of great interest. One of these 
is the Leptocephalus of the American eel, Anguilla chrysypa. We have taken pleasure 
in associating the name of Grassi with this species in recognition of his identification 
of Leptocephalus hreviceps with the European eel. Incidental to the identification of 
the Leptocephalus of the American eel, we have found that the American eel has but 
105' to 110 segments, several less than the European eel possesses. Another interest- 
ing species is Leptocephalus diptychus, in which the color of each side is asymmet- 
rically arranged as to the distance between successive spots, but the blending of the 
color of the two sides of the transparent creature gives the effect of symmetrically 
arranged markings. 
Most of the species described here are new and belong unquestionably to different 
adult forms. Concerning others we are not at all certain whether the species belong 
to different adult eels or are different stages of the same eel. Thus we are not certain 
whether L. amphioxus and L. rex are different stages of the same form or not. The 
same is true of L. gillii and Z. latus. 
The name Leptocephalus was originally proposed in 1777 for Z. morris ii , the larva 
of the conger eel. Since this name is older than any other that has been applied to 
the adult conger, it has recently been appropriated by Jordan & Evermann (Fishes 
of North and Middle America, p. 353) for the conger eel. This leaves us without a 
distinct appellation for larval eels of the Leptocephalus type. It might be advantageous 
to use the second name proposed for a larval eel, if the possibility of losing it as soon 
F. C. B. 1901— 6 81 
