Decapo da — Br achy lira . 
elongated, extending over the front edge of the moutli-frame. The Table-case 
latter character recalls the Oxystomata, which the members of this No - 15 - 
family also resemble in their sand-burrowing habits. Corystes 
cassivelaunus (Fig. 49) is a common British species. The claws 
or chelipeds are much elongated in the male. The antennae 
are much longer than is usual in the Brachyura, and each bears 
a double row of bristles so arranged that when the antennae are 
Female. Male. 
Fig. 49. 
Corystes cassivelaunus (slightly reduced). [Table-case No. 15.] 
brought together they form a tube, through which respiration can 
be carried on while the animal is buried in sand. 
In the tribe Catometopa the carapace is typically more or less Table-case 
quadrate, with the front strongly bent downwards : the mouth- No - 16, 
frame is square ; the genital ducts of the male open on the sternum. 
A large proportion of the Crabs belonging to this tribe live on 
land, in fresh water, or between tide-marks on tropical shores. 
Only the chief families are illustrated in this Case. 
The family Geocar ciniclae (or Gecarciniclae ) comprises the true 
Land-Crabs, although some members of the other families also 
