ally carried over the surface of the yolk as the blastoderm 
824 General Notes. [ September, 
The young mud-minnow leaves the egg on the sixth day, at 
which time it measures 5™™ in length. A bilaterally symmetri- 
cal net-work of blood-vessels is developed beneath the outer sac 
covering the vitellus, the blood-channels being excavated in the 
periblastic and cellular splanchnopleural covering of the latter. 
The oil-drops soon rearrange themselves on the anterior, lateral 
and ventral aspects of the vitellus, Three days after hatching the 
air-bladder becomes apparent as a fusiform vesicle behind the 
pectorals and above the foregut, when the young fish is viewed 
as a transparent object. 
Pigment is rapidly developed upon the upper and lateral aspects 
of the body, and by the sixteenth day the larve have become 
pretty dark in color, when observed from above. 
Immediately after hatching it is observed that there is a par 
projecting lobe at the end of the tail. Into this lobe the notocho 
extends. This terminal lobe of the tail is much narrower than 
the portion of the caudal lobe just in advance of it. As develop- 
ment proceeds it also becomes longer and more cona 
This terminal lobe of the tail of the larval mud-minnow 1s ee y 
homologous with the opisthure of the larval Lepidosteus and ei 
adult Chimera monstrosa. It is certain that it is subsequen y 
absorbed, since the more advanced stages prove that the wy a 
the permanent caudal fin are developed far in advance oO 
opisthural lobe above described. ; : 
There is a slight tendency to form an opisthural lobe in ret 
of the pike, but the larva of none of the teleostean forms r e 
studied approach the Rhomboganoids so closely in ree ee 
manner in which the tail is developed as Umbra.—/ohin A. Ayaer- 
e pres- 
ence of a well-developed zona radiata, which is thickly feos 
with very fine filaments, such as are found on the eggs = hast any 
longirostris, but much finer. The writer is not aware ri 
such filaments have hitherto been detected on the «ee enidia, 
Cyprinodont. As in the cases of Belone, Exoccetus,. so as 
etc., these filaments intertwine with those of adjacent eggs, alge, 
to bind the latter into masses or clusters which lodge upo ‘duritg 
etc., and thus suspended receive more or less measure nearly a 
our 
days, at a temperature ranging from 55° to 63° ie in 
The oil-drops are small and numerous, and are € 
. du- 
the vitellus, a little to one side of the blastodisk, and r openi: 
à s 
: H 
