16 
nished with external branchiw, something like those of the newt, 
and before it is capable of enjoying a separate existence in the world 
of the sea, these have to be absorbed, and the internal gills 
developed. The growth of the young fish, and the changes that 
take place in its organisation are rapid as it advances towards 
maturity, and at the end of the sixth month——the yelk-bag being 
entirely absorbed, and the gills perfect—it issues from the square 
end of the egg, a well-formed young dog-fish, about four inches 
long, marked and spotted like its parents, and able to take food by 
the mouth. We have now about a hundred and fifty of them alive. 
I am glad to be able to add that the young dog-fishes bred at the 
Brighton Aquarium have been found valuable material for one of 
the greatest contributions to modern science, viz., the masterly 
treatises by my distinguished friend, Professor W. K. Parker, on 
the development of the embryo skull. If one of the egg-cases, 
containing a young embryo fish be cut open, and its contents 
transferred to a deep watch-glass full of sea-water, and placed 
under a microscope, a spectacle will be presented which none 
could regard without admiration. The circulation of the blood 
through the branchice will be seen even more distinctly than 
in the foot of the frog, whilst within the umbilical cord will be 
visible two great vessels. Through these veins the blood will be 
seen passing in contrary directions, one of them conveying it 
from the heart of the fish to the nutrient sac, from which it 
travels by the other back again to the heart. Passing on to a 
description of the eggs of the rays, Mr. Lee said the empty cases 
of the skate and thornback-ray, known as ‘‘ mermaids’ purses,” 
‘¢ skate-barrows, &c., were familiar objects of the sea-shore. These 
black horny cases are about three inches long and two inches broad, 
flat on one side, slightly rounded ‘on the other, and havinga thin, 
tapering projection from each of the four corners, like handles of 
of a hand-barrow, a butcher’s tray, or a police “ stretcher.” A 
person picking up some of these plentifully-strewn items of flotsam 
and jetsam, would find them empty, or at best containing a little 
water or wet sand. The young fish had arrived at maturity and 
escaped. ‘Tired of being left by its mother locked up in the house 
by itself, it had made bold to force the door, and seek its living in 
the outside world. How? The tenement seemed all secure and 
undisturbed, but it was nevertheless certain that the youngster had 
got out and the sand had gotin. A moment’s thought would tell one 
that if the door was forced, the runaway had no means of repairing 
the fastenings, and that where the fish had made its exit the sand 
found ingress. Pressing with thumb and finger on the yielding case 
of flexible horn, out would come sand and water through a pre- 
viously unnoticed transverse rupture, or slit, across one end of the 
case. How was this made? By the young fish whose temporary 
prison it once was, and by a process similar to that which he had 
