RECORDS OF W.A. MUSEUM. 
234 ] 
The following are the principal characters of the species. 
Carapace finely pitted above ; large specimens have numerous 
sub-acute tubercles on the back and sides behind the cervical groove 
which can be traced more or less distinctly in all but the smallest 
specimens. There are usually four sharp spines on the sides 
directly behind the cervical groove. Back with five keels, of which 
two are backward extensions of the lateral margins of the rostrum. 
The median keel rises between these last and may run back to the 
cervical groove, or terminate well before that point. The outer 
keels each end in an acute spine anteriorly. Rostrum nearly 
horizontal or obliquely smooth in younger specimens but with 
numerous large and rounded tubercles in adults. 
Chelae slender in young, massive in adults; the breadth varies 
from more than four to about two-and-a-balf in the length, according 
to age. I ney are smooth and rounded above, with minute scattered 
pits which are more crowded on the outer surface. The inner 
margin is not raised upwards, and is usually provided with seven or 
eight tubercular denticulations. there is no tomentose patch on 
the upper surface in any of my specimens. Ringers either meeting 
along their whole length or with a greater or smaller gape between 
them. 1 hey each have a large tubercle on the basal halves o 
their inner margins, with one or two smaller ones behind them. 
Wrist with a moderately large internal spine. 
This large and handsome species is apparently confined to the 
rivers of South-western Australia. Of the series examined the 
gt eater number were obtained in the Harvey River, seven miles 
above Harvey; one is from Korijekup, Harvey River ; one from 
Margaret River , one from Balingup Brook ; and three from the 
Warren River. Mr. W. B. Alexander informs me that it is known 
as the Marron, and that he has also seen it from Kojonup. 
Genus PARACH AEKAPS, Smith. 
PARACHAERAPS BICARINATUS, Gray. 
Parachaeraps bicarinatus, (Gray) Smith, Proc Zool. Soc. 1012 pt I p 16^ 
pi XXI., and pi. XXVI., figs. 15-24. 
Smith has described specimens of this species from Victoria, 
and states that “ it is widely distributed all over Central, Northern, 
and Western Australia and in Queensland.” Unfortunately, the 
