10400 TREUBIA VOL. Il, 1. 
The number of the little hook-like spines forming two bands on 
either side of the body has increased considerably and each band now 
consists of a double row of spines. In later stages these spines spread 
over the whole surface of the body which then feels like a shark’s skin, 
the tips of the spines being all directed backwards. They remain arranged, 
however, more or less distinctly in longitudinal rows. 
In the results of the Siboga-expedition, page 101, WEBER gives a 
figure of a Fistularia-larva of exactly the same length (45 mm). In two 
respects, however, it differs from mine. In one of these, I suspect 
that the artist has made a mistake. It is not the ventral one of the 
two fin rays constituting the caudal flagellum, which is the longest, but 
the dorsal one. I suggest that in making this figure the artist has not 
observed an accidental torsion of the body under the cover-glass — as 
often occurs —, which caused the tail to be in a reversed position. 
In the second place in my larva the fine spines are not yet distributed 
indiscriminately over the whole surface of the body, but arranged in two 
pairs of lateral rows. Evidently the larva figured by WEBER is in a further 
advanced stage of development than mine, although the length from the 
tip of the snout to the end of the caudal flagellum is the same (45 mm). 
This appears also probable from the fact that in WEBER’s larva the caudal 
flagellum is relatively longer than in mine. In my specimen the flagellum 
measures only 8 mm and the body consequently 37 mm, whereas in WEBER’S 
larva the flagellum is 16 mm long and the body 29 mm, Thus we 
cannot wonder that the distribution of the spines is likewise in a further 
stage in WEBER’s larva, in the same way as is the case with the growing out 
of the flagellum. We often may notice similar disparities in the growth of larvae: 
some grow faster in length, in others differentiation proceeds more rapidly. 
STEINDACHNER and GUNTHER (1880), in the latters Report on the Shore 
Fishes of the Challenger expedition (p. 68), have distinguished two 
closely allied species of Fistularia, differing slightly but constantly in the 
sculpture of the head and by the fact that in one the skin is smooth, in 
the other rough to the touch. They leave the name serrata, formerly used 
indiscriminately for both, to the species with a rough skin, while the one 
with the smooth skin is baptized Fistularia depressa. Both species occur 
in the Indian waters, as may be seen e.g. from WEBER’s Report on the 
Fishes of the Siboga-expedition and as I can confirm myself from material 
present in the Laboratory here. However, the differences between both 
species are evidently too slight to allow us to distinguish them in such 
young stages as described in the present article. It appears from my observations 
that in young stages the skin is covered in both with the fine hook-like 
spines. In Fistularia serrata they persist till in the adult state, as the 
„minute asperities” observed by the above authors and which render the 
skin rough to the touch. In Fistularia depressa they disappear in older 
stages and, just as with the appearance, this proceeds from the front 
