Leptocepbdus acuticeps • — ORTON 
187 
K 
Fig. 1. Leptocephalus acuticeps. Outline of 107-mm larva. Shows internal three-spot pattern and associated 
morphological characters; rest of pigmentation omitted. Somites 50 and 63 outlined to show their general 
configuration; rest of somites omitted. 
G, gut; K, kidney; L, liver; P, pylorus. 
nal flaps but no definite respiratory filaments. 
Both larvae have well-developed pseudobranchs. 
The pectoral fins are moderately small. On the 
107-mm larva the fin base is on the fourth 
somite, and the adpressed edge of the fin mem- 
brane reaches about halfway across the sixth 
somite. On the 124-mm larva the pectoral is 
one somite farther forward; its base is on the 
third somite and its free edge reaches the fifth. 
The caudal fin ( Fig. 3 ) is well defined but the 
narrow hypurals are not very heavily chondri- 
fied, and their combined vertical diameter is 
only slightly greater than that of the notochord 
and spinal cord together. The three or four cau- 
dal rays quite fully occupy the available space, 
and hence few if any additional rays are likely 
to form on older larvae. The last basal elements 
of the dorsal and anal fins are in contact with 
the hypurals. The dorsal fin begins as a barely 
perceptible thickening at about the 149th so- 
mite on the 107-mm larva, and at about the 
153rd somite on the 124-mm larva. (Position of 
a structure or color-pattern element in relation 
to a numbered somite is determined by extend- 
ing a vertical line from the feature in question 
and counting the somite that forms its midlateral 
angle where this vertical line meets the body 
axis.) The somites total 182-187, of which 
158-161 (about 86% of the total) are preanal 
and 24-26 are postanal. A major vertical artery 
extends down from the aorta to the viscera at 
the 16th or 17th somite, and another one (or 
two very close together) at the 26th or 27th 
somite. The narrow liver is moderately long, 
very thinly tapered anteriorly and slightly thicker 
toward its more bluntly pointed posterior end. 
It begins at the 13th somite in the 107-mm larva 
and at the 8th somite in the 124-mm larva; In 
each it ends at about the 27th somite. Since the 
pylorus is at the 25 th somite in each larva, the 
liver subtends about 12 and 17 prepyloric so- 
mites, respectively. The gut is a simple straight 
tube, with no undulations or regional enlarge- 
ments. The slightly thickened kidney parallels 
the top of the gut for about 36 or 37 somites 
behind the pylorus, to somite 61 or 62 (Fig. 4) . 
There is a conspicuous vertical artery at somites 
50-51 (damaged on the 124-mm larva). The 
major renal artery leaves the body axis at so- 
mite 58 or 60, and the renal portal vein at somite 
63 or 64. The artery is vertical, but the vein 
slants forward. Behind its junction with the 
renal portal vein, the kidney narrows abruptly 
to form the thin, scarcely visible duct that con- 
tinues along the top of the gut for an additional 
97-99 somites and terminates directly behind 
the anus, between somites 158 and 16 1. 
Pigmentation. The pigmentation is unusual, 
compared with that of other leptocephali in 
general, both in the complexity of its pattern 
