F.
1. - Carapace convex on the sides, rather rugose on the sides behind, the
front only slightly produced and edged with a toothed raised margin not
reaching beyond the front edge of the lower orbit, and with a very short
ridge at the middle of each orbit behind; the hands compressed, rather
rugose, edge thick and toothed: wrist with four or five conical spines on
the inner side, the front the largest: the central caudal lobe, broad,
continuous, calcareous to the tip, lateral lobes, with a very slight
central keel; the sides of the second abdominal rings spinose.
Inhab. Van Diemen's Land.
Mr. Milne Edwards, (Archives du Museum, ii. 35. t. 3.) has recently
described a species of this genus from Madagascar, under the name of A.
MADAGASCARIENSIS, which is nearly allied to the Van Diemen's Land
species, in the shortness of the frontal process, the spines on the sides
of the second abdominal segment, and in the lobes of the tail; but it
differs from it in the length of the claws, and other particulars.
Madagascar appears to be the tropical confines of the genus.
2. The Western Australia Cray-fish. ASTACUS QUINQUE-CARINATUS, t. 3. f.
3. - Carapace smooth, rather convex, and with three keels above; the beak,
longly produced, ending in a spine, simple on the side and produced into
a keel on each side behind; the central caudal lobe rather narrow,
indistinctly divided in half, and like the other lobes flexile at the
end, the lateral lobes with a central keel ending a slight spine; the
hands elongated, compressed, smooth, with a thickened, toothed, inner
margin, which is ciliated above; wrist with two conical spines on the
inner side.
Inhab. Western Australia, near Swan River.
3. The Port Essington Cray-fish. ASTACUS BICARINATUS, t. 3.f.
2. - Carapace smooth, rather flattened, with a keel on each side above in
front; the beak longly produced, flattened, three toothed at the top;
hands rather compressed, smooth, thinner and slightly toothed on the
inner edge; the wrist triangular, angularly produced in front; the
central caudal lobes with two slightly diverging keels continued, and
like the others thin and flexible at the end, the inner lateral lobes
with two keels, each ending with a spine.
Inhab. Port Essington, Mr. Gilbert.
The A. AUSTRALASIENSIS, Milne Edwards, Crust ii. 332. t. 24. f. 1 - 5.
agrees with this species in the form of the beak, but the keels on the
thorax are not noticed either in the description or in the figure; and
the caudal lobes in the figure appear most to resemble A. FRANKLINII.
As the genus ASTACUS is now becoming more numerous in species, it may be
divided, with advantage, into three sections, according to the form of
the caudal lobes; thus: -
A. The central caudal lobes divided by a transverse suture into two
parts, both being hard and calcareous, and with a small spine at the
outer angle of the suture (PATAMOBIUS, LEACH) as A. FLUVIATILIS of
Europe, and A. AFFINIS of North America, with an elongated rostrum, and
A. BARTONII of North America, with a short rostrum.
