818 General Notes. [August, 
2. The highest major group in the Epicyemate subphylum I 
will call Ichthyes, as it is the only series in which true fin-rays 
are developed, and in all of the forms embraced by the term true 
embryonic fin-rays, or actinotrichia, may be found in the fin-folds 
of the embryo. 
The ovum is provided with a zona radiata, but is entirely with- 
out or has only an inconsiderable albuminous. envelope, rarely 
with loose granules of proteinaceous matter included between the 
vitellus and zona; no chalaze; no calcareous shell, though 
sometimes there may be present in addition an outer tough, 
the intestinal wall. 
a. The first subordinate group under Ichthyes is characterized 
by being ectotrophous, for the reason that the embryo is sessile 
for only a short time, as it soon becomes folded off from the yolk 
and raised upon a hollow umbilical stalk, so that the yolk event- 
ually occupies an apparently extra-abdominal position, or rather it 
lies in a bulbous extension of the abdominal cavity. This series 
embraces the Selachians and Holocephali. 
b. The second subdivision of the Ichthyes is equivalent to the 
Teleostomi of authors. These, as far as known, are ccelotrophous, 
that is to say, the embryo is sessile upon the yolk, and is never 
folded off so as to develop a stalk; the yolk is intra-abdominal 
and below the intestine and between the latter and the greatly 
distended somatopleure. 4 
The Teleostei, Holostei and Chondrostei belong here, and it 
will be very surprising if any embryological characters are ever 
found which will separate the archaic Crossopterygians and Dip- 
noans from this series. For the characters of the latter we must, 
1oWever, await the results of the researches of Mr. Caldwell. 
