ON THE BRACHYUROUS DECAPODS OF THE CAPE. 
63 
two minute tubercles at the base of a longitudinal carina. An irregular transverse carina 
stretches out on each side from the last lateral marginal tooth towards the middle of the shell, 
marking out the upper limit of the branchial region. The chelae are marked above with five 
keels on the fixed digit, and three or four longitudinal furrows on the middle finger. The 
second, third, and fourth pair of feet, are compressed, having their third and fourth joints 
bicarinated, and their ungues furrowed. The fifth pair of feet are less bicarinated, and the 
last joint or claw is like the posterior claw of Carcinus mamas, Leach, only more bioad. 
The length is less than an inch. 
8. We now return to the aberrant family Eriphidce, by means of which we pass to Thelphusa 
among the Grapsina. It becomes therefore necessary to point out the families of a stirps 
which is very common in warm climates, and the study of whose manners afforded me much 
amusement whilst I resided in the West Indies. Dr. Milne Edwards calls them Catametopes, 
and says that some of them are “ completement terrestres.” This is an error, however; for all 
these crabs must lay their eggs in water, must pass their infant state in water, and must, 
during their future life, return periodically to the vicinity of water. The land-crab par excel- 
lence* G eg arcinus ruricola, Lat., in this respect, does not differ in economy from other 
Brachyurous Decapods, nor does it retire many leagues from the sea. In our small West 
India islands it may be found all over them ; but in Cuba it has its limits, which are confined 
to a certain distance from the shore. 
Stirps. GRAPSINA, or Square Crabs. 
jfmntltfSh 
Aberrant Groape. 
Tigellus of external pedipalps 
never inserted at the mid- 
dle of the apex of third 
joint. 
'1 Thelphcsid^;, M. E. 
Fresh Water Crabs. 
2 Gonoplacid.e, M. E. 
A 
Deep Shore Crabs. 
3 OcyfodidjE, Leach. 
- Low Shore Crabs. 
f Ocular peduncles short. Tigellus of external pedipalps 
<J never inserted at the outer angle of third joint. Scape 
of the palpi unidentated on the inside, 
f Ocular peduncles long. Tigellus of external pedipalps in- 
•< serted at the inner angle of third joint. Scape of the 
L palpi unidentated on the inside. 
f Ocular peduncles long. Tigellus of external pedipalps al- 
< ways inserted at the outer angle of third joint. Scape 
C of the palpi not dentated. 
Normal Groupe. 
Grapsi, Dehaan. 
4 Grapsid-e, M. E. 
Salt Water Crabs. 
Tigellus of external pedipalps < 
inserted at the middle of 
the apex of third joint. 5 
Palpi never dentated. 
Gegarcinid-e, M. E. 
True Land Crabs- 
( Shell depressed, and the whole structure such as to render 
| these crabs unable to retire far from the sea. 
f Shell convex in order to contain a certain quantity of water, 
| enabling these crabs to travel great distances on land. 
9. Dr. Smith has brought specimens of all the above families of Grapsina except of the 
Gegarcinidce. The first family Thelphusida has the genital organs of the male placed nearly 
as in the last stirps Cancrina, with which it is osculant. But the other families of Grapsina 
have the genital orifices of the male placed in a transverse groove hollowed out on the 
sternum. Both the Thelphusidm and Gonoplacidce being aberrant families, agree with the 
Cancrina in having the scape of their palpi unidentated on the inside. 
