78 General Notes. [ January, 
a disk is formed by the confluence or coalescence of the pectoral 
pair of fins. 
The adult toad-fish burrows a cavity under one side of a sub- 
merged boulder, and to the solid roof of this cavity the female 
attaches her ova in a single layer. The eggs are very adhesive 
and quite large, measuring about one-fifth of an inch in diameter. 
Like the male cat-fish, the male toad-fish assumes charge of the 
adherent brood of eggs and remains by them until they are hatch- 
ed and subsequently become free. 
The egg-membrane or zona radiata is very firm, and adheres to 
the under surface of the stone by a discoidal area about 3"™ 
in diameter. The free globular pole of the egg is accordingly di- 
rected downwards. The germinal disk is developed at the lower 
pole and gradually spreads so as to enclose the vitellus from 
below upwards. The result is that the embryo is formed upon 
the lower or free pole of the egg, where it develops until it finally 
ruptures the egg membrane, when it may be said to have hatched, 
but, unlike all other types of fish-embryos known to me, the young 
fish does not at once drop out of the egg-membrane when the latter 
is ruptured. This is prevented by the adhesion of the ventral (now 
upper) pole of the yolk-sack to the inside of the egg-membrane 
just before the latter is ruptured. Just how this secondary adhe- 
sion of the yolk-sack is effected has not been determined, but the 
adhesion persists until the embryos are considerably over one-half , 
inch in length. 
In the course of the development of other parts, the yolk-sack 
is finally constricted horizontally round the middle below the 
body of the embryo, and becomes hour-glass-shape. This is due 
in part to the down growth of the mesoblastic somites on either 
side of the yolk from above; as a result of this a part of the yolk 
becomes intra-abdominal while a part of it remains for a time in 
the lower bulb of the yolk-sack and outside of the true abdominal — 
cavity. Eventually the whole of the yolk becomes intra-abdomi- 
nal; this is due in part to its further absorption and the further 
development of the abdominal walls of the embryo, but during 
all of this time, or until yolk-absorption is completed, the embryo 
remains adherent as described above. At this stage the embryo 
is so far developed that it would be recognizable as belonging to 
the genus Batrachus. 
The pectoral and pelvic fins develop as very short folds which 
are close together, the latter arising almost immediately behind 
the former. In the course of further development, the pelvic 
fins are suddenly translocated forwards in advance of the pectorals, 
and are finally brought to lie near the constriction in the yolk-sack 
and just above the lower bulbous portion of the latter. It will 
therefore be obvious to any one that neither the pectoral nor pel- 
vic fins have anything to do with causing the adhesion of the em- 
bryos, for both of these fins arise far above the point where the 
young fish is adherent. i 
