of the Fishery Board for Scotland. 73 
following the scent dispersed by the current of water flowing through the 
box. 
One little lobster took up its abode for a day or two in a Purpura 
shell which lay on the sand that covered the bottom of the aquarium, 
but when it attracted attention, it had excavated in the sand a hole 
below the shell, and in it it lay. The hole was deep to the front, and 
was a neat fit. The lobster pushed out a quantity of sand, two armsfull, 
in front of it, and removed larger grains of sand and a little piece of 
debris with its maxillipedes. When returning from a promenade round 
its prison it carefully tested its lair before it backed into it. It was alone 
in the aquarium. Now this lobster did not imitate an adult or any other 
young lobster in taking up its abode in the shell, or in digging a cave in 
the sand. When food was tumbled in it seemed to resent its approach. 
It appeared to be attracted by the scent at first, and then it put some fresh 
mussel that tumbled into its cavity out of the hole, while some mussel 
that was apparently old was left in. It was noticed that the mussel stuck 
to the pereiopods. 
Another little lobster, in its wandering about among the sand and mud, 
got its pereiopods and maxillipedes covered with fine debris which, no 
doubt, consisted, in considerable part, of diatoms. It was observed to 
pick off the debris and put it into its mouth. Sometimes the mud in 
the aquarium was all punctuated as if it had been probed all over with 
the legs of the lobster. 
THE LarRvaAL STAGES. 
In the lobster the zoéa is a much more specialised organism than in 
certain of the other decapod crustacea, e.g. Crangon and Carcinus. One 
important respect in which the former differs from the two latter is in 
the possession of functional gills. The presence of the gills determines 
the form of the appendages concerned in the respiratory function, viz. 
the second maxilla, and the maxillipedes which are employed in securing 
a circulation of water through the branchial chamber. The gills and 
their arrangement being very nearly similar to the condition in the 
adult, it follows that the function of the appendages is that which they 
perform in the adult, and their form is therefore practically that cf the 
adult. In Crangon and Carcinus the maxillipedes have no respiratory 
function to perform in the zoéa ; they and the second maxilla are in form 
quite dissimilar from the adult condition. The adult form of these 
appendages are similar but not identical in the lobster and Crangon. 
The stages which will now be described have not been determined by 
following a lobster in its successive moults. They have been dis- 
criminated from the general collection of larvee which were developing 
in the hatchery. In the case of the higher stages, e.g. last zoéa stage, 
megalops, first and second young stages, the casts connecting adjacent 
stages were observed. 
During the research it was found necessary to redissect this form 
which has already been treated by Sars and others, while the American 
species has been worked out by Smith and Herrick in elaborate detail, and 
profusion of drawings. 
The drawing in the present case represents the condition found in the 
appendage examined. The opportunity did not occur to dissect several 
zoée of the same stage with a view to determine the variation in each 
limb, and from that to fix the normal condition. When a comparison 
has been instituted between the limbs of different zoéz, variation in the 
hair at Sera and in the nature of the hairs themselves, has been 
noted, 
