THE ZooLocist—APRIL, 1876. 4857 
with the species. It was during these active nocturnal movements 
that the fish struck against the rockwork of their tank and came to 
an untimely end: this mortality, however, was soon arrested by 
placing a dim light over their tank, which illuminated the outline 
of the rockwork just sufficiently to enable them to recognise and 
avoid it. With this dim light the fish still retained their active 
habits, and it was noticeable that during these night hours they 
were more than ordinarily alert for food, dashing vigorously at any 
entomostracan or other minute organism that passed through the 
water. This circumstance would seem to explain why ‘ drift-net’ 
fishing for herrings can only be carried on successfully at night, 
that being the time when the fish rise to the surface of the water, 
to feed on the innumerable organisms that there abound. They 
are, in fact, so ardent at such times in pursuit of their food that 
they needlessly strike into the meshes of the net and get caught, 
just as the individuals under artificial conditions dash against the 
rockwork of their tank, if sufficient light is not provided them for 
its avoidance. This plan of dimly illuminating the whitebait tank 
was practised with equal benefit in association with other species 
that exhibited a tendency to injure themselves during the dark hours 
of the night, such species again being usually free rangers of the 
sea. The picked dogfish (Acanthias vulgaris) was one of these, 
and a variety so given to rendering itself an unsightly object by 
knocking its head against the boundaries of its tank, till it lays 
the cartilage of its snout quite bare, that it is frequently refused 
admittance in aquaria- Observations made at the Manchester 
Aquarium, however, revealed that this self-mutilation was invariably 
effected during the night, and a small light enabling the fish to see 
and avoid the rocks was found an effectual preventive remedy.” 
But this is not the only success to which Mr. Kent lays claim: 
another is the artificial cultivation of the lobster; this, how- 
ever, does not appear so entirely complete. I hope, not only for 
Mr. Kent’s credit, but from its importance as a commercial enter- 
prise, this second success may rival the first: here it is :— 
“A remaining subject that occupied my attention at the Man- 
chester Aquarium related to the artificial cultivation of the lobster. 
A remarkably large shoal of this crustacean was hatched out from 
from a fine hen in the summer of 1874, and a number of these were 
isolated in small glass vessels, and reared successfully through their 
numerous singular metamorphoses, until, at the end of two months, 
