H.—ls

22

arrival on the 6th March, 1908. Ten of them (sexes doubtful) cast during May-July. Two of them produced a full batch of eggs at the end of June, hut these very soon became detached, as the bottom of the pond was unsuitable, being of soft mud, and at that season considerably overgrown with clumps of filamentous alga?. So far as 1 am aware, none of these had carried eggs the previous year. Many of these females moulted during November and December, and they were all placed in the No. 3 pond for spawning purposes on the 10th December, 1908. Six males were put in along with them. The first spawned on the 27th December, 1908, one month earlier than the first of the previous year. They have not yet been examined, but, as they are sticking very closely to their shelters, and an occasional one is seen with the abdomen bent under, it is very probable that most of them have spawned. Casting. —The actual process of moulting has only been witnessed in the ponds on one occasion. In most cases this takes place during the night. The cast shell is usually found entire, lying upside down on the bottom of the pond. When about to moult the lobster seeks a position as far away from the others as possible. The shallow end of the pond is almost invariably chosen. A lobster that is about to cast becomes very vicious on the approach of an intruder. On the 3rd September, 1908, a male lobster was seen to be behaving in a very peculiar manner in the shallow end of the pond : it would walk along the concrete dividing-wall for a. distance of about 5 ft., halt, and then, turning round, would retrace its steps the same distance in the opposite direction. In this manner a rut several inches deep was formed in the gravel, and at one end of this the lobster scooped out a hole about 4 in. deep and 12 in. in diameter. The shell was very dirty and overgrown with weeds, shells of serpula, &c, and a slight opening could be seen between the carapace and the first abdominal segment, and the lobster was evidently about to moult. When the pond was run down at low tide the lobster had to be driven awaj ? to the deeper end to prevent its being stranded. As soon as the depth of water allowed, the lobster resumed its peculiar walk, and continued to do so throughout the night and the following day. Moulting commenced at 4.30 p.m. that day. The lobster laid over on its side with the large claws in a direct line with the body. The opening before observed between the carapace and abdomen commenced to widen, so slowly as to be almost imperceptible, the cephalic shield being gradually worked forward until at right angles to the abdomen. No violent effort was made by the lobster ; the process was slow and regular, and continued so until the tip of the rostrum was freed from the pressure of the posterior edge of the cephalic shield. The whole of the anterior portion of the body, with the exception of the large claws, antennae, and walking-limbs, was now dear of the old shell, and gradually resumed its normal position in relation to the abdomen, the remaining limbs being withdrawn during this straightening process. The lobster was by this time practically over on its back, ami by a few violent movements, somewhat similar to the action of the animals when swimming, the abdomen was withdrawn from the told shell. The process occupied thirty-five minutes. *rhe habit of scooping out a hole in the gravel has been noted on several occasions, and the newly moulted lobster has been found lying alongside the cast shell. The shell is usually cast entire, and by removing the gelatinous skin that is cast with the shell, and replacing the parts in their respective positions until dry, an exact model of the lobster is obtained. The cast shells of all females are preserved and labelled in this manner, and, as each has some characteristic distinctions in the way of size, lost or regenerating limbs, scars, spines, &c, it is an easy matter to distinguish them so as to bring them indoors in their order when the eggs are nearly ready to hatch. The photograph is of a cast shell of a male. (Plate 3.) The external eggs when newly spawned vary considerably in size and colour. They are from 1"8 to 22 millimeters in diameter, and usually of a very dark-green colour. Some are almost jetblack. The photo (Plate 4) is of a female that spawned in February this year. Little difference in size of the eggs is noticed until about the last month of development, when they increase in some cases to as much as 3 millimeters in length, but at this time they are not spherical, but oblong, and conform somewhat to the shape of the contained embryo. The eggs spawned in January were not examined until the 16th June. Their condition at this period has already been given. From this date onwards one or more eggs were examined daily. The green yolk is gradually absorbed as development proceeds; the colour of the pigmentation of the embryo is usually of a very bright red, but in a few cases it is streaked with or wholly green. During the last month sharp spasmodic movements are seen, in some cases so violent as to move the egg from under the object lens. Three instances of twin embryos contained within the one egg-capsule were observed. In two of these cases the one larvae issued earlier than the other, and a rotary motion was maintained until the second larva? was free. The hatching of the one brood extended over about thirty days. This is longer than the time given by various workers, and is much longer than the time taken to hatch the brood of all local Crustacea dealt with at the station. Although every effort was made, it is somewhat difficult to account for the loss of so many eggs during the last month of fosterage. XV will be seen by the foregoing account that very few eggs are lost during the first nine months, and I am very much inclined to the belief that in the warmer waters of the Gulf Stream the majority of these eggs would by this time have hatched out, and the loss of eggs would have been very slight. Another probable cause is the not unnatural neglect of the female to properly aerate and cleanse the eggs when kept for a long time in close confinement. The effect of this neglect is made apparent about the seventh month, when the outer layers of eggs commence to become slightly coated with diatoms, algse, sediment, &c. This growth appears in time to rot the outer shell, which is in reality only the attaching membrane, and the egg becomes detached with the slightest movement of the abdomen. The inner shell is very thin, and if the egg is left on the bottom of the tank the shell is soon pierced, and the contents are seen being devoured by parasitic infusoria. There are, no doubt, other contributing causes, such as the bright light in the glass tanks, and, towards the latter part of the experiment, the presence of excessive numbers of diatoms, the spores of alga?, infusoria, &c, in the supply-tank water. For the same reason —rust, sediment, <fee, owing to having