1869.] LETTER FROM MR. G. CLARK. 3 
A communication was read from Mr. George Clark, of Mahéburg, 
Mauritius, Corr. Memb., on the Squill of Mauritius (Squilla styli- 
fera). After a detailed account of the external characters of this 
group, Mr. Clark proceeded to observe as follows :— 
* The Squills are mostly nocturnal animals, living in holes ; hence 
it is not surprising that they are little known. It is evident at a 
glance that the position of their branchial apparatus renders it im- 
possible for them to carry their eggs as Lobsters and Shrimps do ; 
such an arrangement would stop their breathing. Cuvier states 
that he never saw one bearing eggs; and it was with no small satis- 
faction that, while making researches on the history and habits of 
these creatures, I learnt from Dr. Power he had seen this; and a few 
days after I had the satisfaction of witnessing it myself. The roe 
of the Squill is very curious, and occupies the whole length of the 
body. The eggs when first extruded form a compact mass, which 
the female holds between the three pairs of jaw-feet. As this mass 
expands it forms a loose kind of tissue, somewhat similar to a fleece 
of wool. Little by little, as the eggs enlarge, the texture of the 
mass becomes looser, until the larvee are hatched and swim off to 
shift for themselves. In the first period of incubation, if I may so 
call it, the female will hold her eggs even when caught; but the 
further advanced they are the more readily does she drop them, 
possibly on account of their cohering less firmly. I believe the 
female must fast while carrying her eggs; for I have found the sto- 
machs of those taken at that period quite empty, but generally full 
at other times. When first hatched the larvee are of a delicate yel- 
lowish green, and are very active. As they grow they assume a 
mottled grey, and the swimmerets and legs become pea-green. The 
green gradually increases in brightness; but it is not till they have 
reached a length of three inches that the colours of the adult appear. 
The male is then of a beautiful bluish green, with the jaw-feet, the 
swimmerets, and the branchiz, as well as the antenne and the fim- 
brie which border the different organs, of a cherry-red. The female 
is clouded with brown and grey, presenting much the appearance of 
tortoisesnell, and the red about her is much less vivid than in the 
male. ‘The young Squills inhabit holes in the sand, near low-water 
mark, ‘The old ones are never found here, but reside in the patches 
of coral which are scattered over the shallows. Both old and young 
have invariably two entrances to their holes; and the adults always 
stop these with a plug of fine seaweed. They do not swim swiftly ; 
and in places where the water is not deep enough for them to swim 
their principal organs of progression are their large jaw-feet, which 
they thrust forward as a man would do striving to get along on the 
points of his elbows. I believe these limbs also serve them to make 
their holes, as they are often considerably worn on the joints. The 
motions of the Squill are very different from those of a Shrimp or a 
Lobster, being much more like those of a caterpillar; hence the 
little Creoles call the young ones ‘Chenilles de mer.’ The extensor 
muscles seem to act much more powerfully than the flexors; and it 
is by the former that the vigorous motion is produced which inflicts 
