of the Fishery Board for Scotland. 69 
makes the period one of three zoéa stages, and between hatching and the 
arrival of the young at the megalops condition there elapses from eight 
to eighteen days. Saville Kent said that the European lobster reached 
the megalops stage at about the sixth cast, z.e. five stages precede it, viz. 
the protozoéa and four zoéa stages. A month or six weeks are occupied 
in arriving at the stage beyond the megalops, which I have denominated 
the first young stage. My own observations lead to the conclusion that 
the period just mentioned will very rarely be exceeded ; it is probably often 
as short as one month. Certain larve which were in the zoéa condition 
in October and November remained for five weeks in one stage, however. 
Sars illustrates three zoéa stages. Chadwick has published a descrip- 
tion of-the protozoéa, three zoéa stages, megalops, and first young stages. 
The time occupied by each stage, with the exception of the protuzoéa, is 
given as a week. 
Rathke says the maxillipedes and pereiopods have a general resem- 
blance to the legs of schizopods, viz., Mysis, but the resemblance is 
lost in the fifth pereiopod. In the denomination of the larval lobsters 
it has been customary, therefore, to refer to the early pelagic stage as 
the ‘‘mysis” stage. ‘This is due to the fact that its pereiopods resemble 
those of Mysis, in having setz-bearing exopodites. But this is an onto- 
genetic, not a phylogenetic, character, as the name is apt to imply. The 
main swimming organ of a zoéa is the exopodite, and the number of 
setose exopodites is directly proportional to the size of the larva. The 
little elongated zoéa of the shrimp (Crangon vulgaris) has three pairs of 
exopodites in its first stage, but its increase in bulk in the third zoéa 
stage demands additional swimming power, and a fourth pair of exopodites 
appear, viz. attached to the rudimentary first pereiopod.* In this case 
the exopodite is developed, and becomes functional in the third zoéa stage, 
whereas the chela becomes functional for the first time on the megalops 
stage, 2.e. the sixth larval stage. The exopodite of the chela at the same 
time vanishes, while the other exopodites, those of the maxillipedes, are 
reduced and function no longer for swimming. In the case of the 
lobster larva we have to deal with a large form, which requires a 
powerful swimming organ. That is secured by the development of 
the exopodites on the pereiopods, but with this difference from the 
shrimp, that the pereiopods themselves are also functionally developed 
—in the form of maxillipedes. The zoéa of the lobster is provided, 
then, with eight maxillipedes, each of which has a setose exopodite, 
On the arrival of this form at the megalops stage the latter disappear or 
are so reduced that they are no longer swimming organs. The quadrant 
shape in which the body of the zoéa is bent, by concentrating the 
weight of the animal, has a direct relation to its propelling organs. The 
tiny zoéa of Carcinus menas has only two pairs of exopodites. It is bent 
in an arc; thereby the weight is concentrated. 
There, appears, then to be no valid reason for departing from the term 
‘‘zoéa” for this period of the life of the lobster. And the term “ mega- 
lops” is an appropriate name for the stage which is analogous as well as 
homologous to the megalops of the Brachyura. It is a transition stage 
between the zoéa and the adult. 
In this country the rearing of lobsters has been carried out by Saville 
Kent, Cunningham, Weldon, Fowler, and Chadwick. On the Continent 
Captain Danuevig has done the most extensive work in this subject ; 
lately Appellof has carried on rearing experiments. 
Many difficulties meet the experimenter in lobster-culture. Questions 
of the food, of the cannibalism of the larvee, and of the mortality which 
* Vide Williamson, 
