FRESHWATER AND LAND CRAYFISHES OF AUSTRALIA 
31 
The above description will not fit any of the hundreds of 
specimens examined. It is apparently a species of Cherax, 
judging by the figure. No mention is made in the text as to 
whether the telson and uropods are membranous. The figure 
shows the telson entirely calcareous, the inner rami of the 
uropods are divided by transverse sutures which may indicate 
the junction of membranous and calcareous portions, hut the 
outer rami are apparently entirely calcareous, without trans- 
verse sutures. The great chelae also differ in the figure and 
the text. 
Genus GEOCHARAX gen. nov. 
Carapace higher than broad, punctate or tuberculate. Cervical groove 
deeply impressed, rounded. 
Abdomen smooth, punctate, or setose; lateral margins rounded. First 
somite with lateral lobes small and rounded. Telson without transverse 
sutures, entirely calcareous. 
Second antennae set at the side of the first, squame large. Upper lip short 
and broad, with a concave arch medianly. 
Lateral processes of sternal keel obsolete, keel continued across posterior 
pair. Vas deferens on simple short papillae on coxae of fourth pereopods. 
Stem of each podobranch laterally produced into a small wing-like expan- 
sion, bearing few hooked filaments. Gill formula 21 epr. 
Genotype Geocharax gracilis sp. nov. 
Key to Species of GEOCHARAX gen. nov. 
Rostrum slender and sharp GRACILIS sp. nov. 
Rostrum broad and blunt LYELLI sp. nov. 
Geocharax gracilis sp. nov. 
(PL I, fig. 8; PI. VI, fig. 26.) 
Length of average adult specimen, 55 mm. 
Rostrum slender, reaching to end of third segment of first antennae, apex 
sharp and upturned; carinae very sharp, straight, carried well back on to 
carapace ; lateral carinae very sharp, each ending in a rounded boss. 
Second antennae slender) reaching to telson; squames large, reaching 
beyond the end of the third segment of first antennae, terminal spines short 
and sharp. Interantennal spine short and broad, pyriform, apex sharp. Eyes 
very large. Median arch of upper lip produced into two sharp, erect 
protuberances. 
Carapace higher than broad, more than twice as long as broad, shorter 
than abdomen. Cervical suture deeply impressed, rounded ; branchio-cardiac 
grooves obsolete, areola very broad. Entire carapace densely studded with 
minute tubercles. 
Sternal keel narrow, sharp, continuous from great chelae across lateral 
processes of third pereopods; lateral processes obsolete, fourth pair small 
and flattened downwards; processes between fourth pereopods very short 
and stout. 
