8 FRESHWATER AND LAND CRAYFISHES OF AUSTRALIA 
system traversed by the oesophagus; possessing a heart and branchial 
respiratory organs. 
“The body is bilaterally symmetrical, and consists of twenty meta- 
meres (or somites and their appendages), of which six are associated 
into a head, eight into a thorax, and six into an abdomen. A telson 
is attached to the last abdominal somite. 
“The somites of the abdominal region are all free, those of the head 
and thorax, except the hindermost, which is partially free, are united 
into a cephalothorax, the tergal wall of which has the form of a continu- 
ous carapace. The carapace is produced in front into a rostrum, at 
the sides into branchiostegites. 
“The eyes are placed at the ends of movable stalks. The antennules 
are terminated by two filaments. The exopodite of the antenna has 
the form of a mobile scale. The mandible has a palp. The first and 
second maxillae are foliaceous ; the second being provided with a large 
scaphognathite. There are three pairs of maxillipedes, and the 
endopodites of the third pair are narrow and elongated. The next pair 
of thoracic appendages is much larger than the rest, and is chelate, 
as are the two following pairs, which are slender ambulatory limbs. 
The hindmost pairs of thoracic appendages are ambulatory limbs, like 
the foregoing, but not chelate. The abdominal appendages are small 
swimmerets, except the sixth pair, which are very large, and have the 
expodite divided by a transverse joint. 
“All the crayfishes have a complex gastric armature. The seven 
anterior thoracic limbs are provided with podobranchiae, but the 
first of these is always more or less completely reduced to an epipodite. 
More or fewer arthrobranchiae always exist. Pleurobranchiae may be 
present or absent.” 
Key to Families of ASTACUBA. 
First abdominal somite of male, and usually of female, provided with 
appendages. 
First antennae each with two well-developed flagella. Outer rami of 
uropods with transverse sutures ASTACIDAE 
First abdominal somite devoid of appendages in either sex. 
First antennae each with two well-developed flagella. Outer rami of 
uropods with transverse sutures. Carapace not vaulted posteriorly 
PAR ASTACIDAE Huxley 
First antennae with the secondary flagellum reduced or absent. Outer 
rami of uropods without transverse sutures. Carapace strongly vaulted 
posteriorly AUSTROASTACIDAE fam. nov. 
Family PARASTACIDAE Huxley. 
Proc. Zool. Soc., Loud., p. 775, 1878. 
Astacidae ( Astacinae ) Dana, U.S. Explor. Exped., xiii, Crust., pt. i, 
p. 520, 1852. 
Astacidae, Miers, Cat. N.Z. Crust., p. 71, 1876; McCoy, Prodromus 
Zool. Victoria, i, Dec. 2, p. 17, 1878; l.c., Dec. 3, p. 45, 1879; 
Spence-Bate, Report Voy. H.M.S. Challenger, Crust. Macr., xxiv, 
1888, p. 192. 
