23

H.—ls

only one supply-tank, and no filtering apparatus —it was not possible to hatch out the detached eggs by means of the Macdonald jars unless they were within a few days from hatching. The method adopted by the U.S.A. Fish Commissioners for artificially hatching lobster-eggs is by collecting as many egg-bearing lobsters as can be obtained for some months before the hatching season commences. The eggs are combed off the swimmerets, and placed in Macdonald automatic hatching-jars. Repeated expel iments with various apparatus have proved that the motion obtained by the use of these jars is by far the best, and the eggs are frequently carried throughout the winter in this manner for as long as six months. The report of the Commission for 1908 is just to hand, and the output of lobster-fry for the year is given as 181,000,000. from 90 to 95 per cent, of the eggs placed in these jars are hatched. A remarkable increase of lobsters is reported by the fishermen along the New England coast, and this is attributed to the tremendous numbers of fry that have been hatched, and liberated in the most suitable localities. The Crab (Cancer pagurus). Twelve crabs were shipped on each of the third and fourth voyages of the " Karamea." Three males and five females on the first and seven males and one female on the second occasion arrived safely, making a total of six females and ten males. Since their arrival several have died, and only seven or eight are now to be seen in the pond ; but, owing to their habit of burrowing in the mud, under stones, and under the foundations of the walls, it is quite possible that others have survived. Owing to this habit, it has not been possible to maintain anything like as close an observation on their habits as was kept on the lobsters. The complete life-history of the crab is well known, and a very complete report by Dr. C. H. Williamson, M.A., B.Sc, will be found in the Eighteenth Annual Report of the Fishery Board for Scotland, 1899. This report deals very fully with the.size at maturity, migrations, fertilisation, frequency of casting, Ac. There appears to be some doubt as to the length of time which elapses between casting and spawning. I am unable to throw any definite light on this. The period of fosterage is given as between seven and eight months. If this is so, the length of time elapsing between casting and spawning is about the same as for the lobster —that is, about two months, as the crabs that cast in January and February hatched their eggs in November and December. The stock of crabs on the 19th November, 1907, consisted of nine males and five females. Two of these females died s i afterwards. On this date they were all placed in the No. 1 pond. A female cast on the 18th January, 1908. One male and one female cast on the 11th February, 1908, and a third female cast on the 24th February. No other casts are known to have taken place. The male crab takes possession of the female a few days before the latter casts, and they were generally seen with the abdomens together in the mud or under the edge of a large stone. On one occasion the male crab was seen to carry the newly cast shell of the female to a distance of about 6 ft. away, and to return at once to the female. The male continues to protect the female for several days after the moult, and it is during this time that coition takes place. The females were not examined until the 30th June, when two were found to be egg-bearing. A third, that could not previously be captured, was found to be egg-bearing on the Bth October, 1908. The eggs are carried externally attached to the swimmerets, and the whole mass is protected by the abdomen. The greatest breadth of carapace of these three crabs was 8 in., and the average number of eggs carried by each individual of that size is three millions. Two of these crabs were placed indoors on the Ist July, 1908. The third one was returned to the pond. When examined on the Ist July the eggs were in a solid compact mass, which completely hid the swimmerets from view. They were of a pale-pink colour, and no trace of the larva' could be discerned. On the 27th October the eggs were lighter in colour and were faintly "eyed"; the yolk-area had considerably decreased in size. On the 19th November the eyes were very prominent : the pulsations of the heart and the flow of the bodyfluid was easily detected under a power of fifty diameters. The eggs were by this time almost transparent, the yolk was reduced to a very small area, the greater part of the egg being quite transparent, with black-pigment markings. There was considerable difference in development, even in the eggs attached to one hair. During the earlier part of their confinement in the tanks the adults remained during the daytime in their shelters, but were often found at night climbing up the dividing-wire, and even walking across the under-side of a wire screen placed across the top of the tank to prevent their escape. This wire netting was about 6 in. above the water, and the crabs were at these times completely out of the water. Towards November they more frequently left their shelters both by night and day, and were often seen standing, as it were, on tip-toe waving the abdomen and swimmerets for the purpose of aerating the eggs. By this time the mass of eggs was not compact, each swimmeret with its attached eggs being waved independently. A good view of the completeness of the circulation of water through the egg-mass was often obtained when the abdomen was close to the glass. The first larva? were seen in the tanks on the 26th November. They were then in the second stage, and congregated at the front of the tank, where the light was strongest. The following day, when siphoning out the bottom of the tank, the end of the siphon was led into a large glass jar, and many thousands of first-stage larva? were found amongst the sand, &c. On emerging from the egg the larvae are not very active, and lie on their sides on the bottom of the tank ; the lateral and dorsal spines are indiscernible, but they appear to either undergo a moult or, more probably, only a. kind of transformation within a few minutes after hatching, and at once commence to ascend towards the surface and swim vigorously about. The adult was at this time almost constantly waving the abdomen, and large numbers of larvae were freed at each movement. The last pair of walking-limbs were frequently probed into the mass of eggs as if to loosen them. Some few of the larva? appeared to me to hatch out directly in the second staji'e. Numbers of these first-stage larva' were kept under observation by Mr. Thomson and myself under the microscope, but no moult was detected, and, as no cast shells were found in the