1883. ] Zoölogy. 797 
indicate the independent origin of these two types of Arthropoda 
from the forms resembling some of the lower worms. We are 
next to look for their occurrence in the Myriopods. Possibly the 
repugnatorial pores of Chilognath may be found to be these 
glands, which open above the insertions of the legs—A. S. Pack- 
ard, Fr. 
SUBMETAMORPHOSES OF FisHEs. — Professor A. Agassiz has 
published the third part of his researches upon the submetamor- 
phoses of the young of bony fishes, including the genera Labrax, 
Stromateus, Atherinichthys, Batrachus, Lophius, Cottus, Cteno- 
labrus, Gadus, Osmerus and some others. 
The caudal fin passes through a heterocercal stage before 
attaining the more or less homoocercal form that characterizes the 
teleost caudal, and the pectorals pass through phases which recall 
those of the Crossopterygia. 
When two dorsals are formed from the continuous membranous 
fold which is the source of all the vertical fins, the posterior ap- 
pears to be usually differentiated before the anterior, but first 
passes through a phase in which the two are confluent, though 
e anal and caudal are already distinct. In Lophius the abnormal 
form of the first dorsal is evident in embryonic stages, and this is 
also the case in other forms with filamentary rays in front of the 
dorsal. The anal is developed before the ventrals except when 
the latter are adapted to some special purpose, as in the young of 
some ganoids,, in some deep-sea fishes and in forms in which the. 
ventral rays form long tactile filaments. The young of Lophius 
Ptscatorius, when about an inch and a quarter long, looks almost 
like a butterfly from the great development of its paired fins, and 
he same occurs in the genus Onus. These extraordinary ven- 
trals represent the enormous appendages of Pterichthys and other 
Devonian genera. 
In the position of the mouth, the cartilaginous skeleton, the 
heterocercal tail, the great pectorals, and the rudimentary dorsa 
and anal fins, the young of existing osseous fishes recall the primi- 
tive fishes, the transformations of which into modern types can 
be traced through the geological ages from the Devonian 
upwards, 
