70 
Guide to Crustacea . 
Table-case and a female are mounted above the Wall-cases at the south end 
isr°. 14. 0 f the Gallery. They were coloured after a drawing of a live 
specimen by a Japanese artist. 
In the family Parthenopidae, the chelipeds are usually much 
more massive than the other legs, and the orbits are well 
formed. The typical members of this family have taken to the 
same habitat as the Oxystomata, burying themselves in sand or 
shingle, and they show many superficial resemblances in the 
shape of the chelipeds, the lateral extensions of the carapace, and 
the disposition of the breathing channels, to such Oxystomes 
as Calappa. In many species, as in the Parthenope horridcc 
exhibited, the carapace and limbs are remarkably rugged and 
uneven. 
Table-ca ;o The Crabs belonging to the Tribe Cyclometopa have the 
N°. 15. carapace, as a rule, broader than long, with the antero- 
lateral borders strongly curved, and the postero-lateral 
borders convergent ; the front is not produced into a ros- 
trum ; the mouth-frame is square ; the genital ducts of the 
male open on the bases of the last pair of legs. With the 
exception of the Eiver-crabs, all the members of this tribe inhabit 
the sea. 
In the large and very varied family .Xanthiclae, the carapace, 
as a rule, is transversely oval, and its surface is often lobulated. 
The species of this family are very abundant, especially in the 
tropics, in the littoral region. Three species of Xantho are 
British, one of w'hich, X. incisus, is exhibited. The vivid 
colours of some tropical species are exemplified by the painted 
specimens of Carpilius maculatus and Zozymus aeneus. To this 
family also belongs the large Tasmanian Crab, Pseudocar cinus 
gigas, a specimen of which is mounted above Wall-cases Nos. 5 
and 6. 
A specimen of Zozyinus aeneus is exhibited which has been 
prepared to illustrate the disposition of the branchial passages in 
Cyclometopa, for comparison with similar preparations of the 
Oxystomata in Table-case No. 13. The third maxilliped has been 
removed on one side to show the quadrilateral shape of the 
mouth-frame (coloured red)-, characteristic of most Brachyura. 
The arrow indicates the course of the respiratory current, which, 
however, may sometimes be temporarily reversed, especially in 
burrowing species. 
The typical members of the family Portunidae (Swimming 
Crahs) may be recognised by the flattened, paddle-shaped, last 
