ON THE BRACHYUROUS DECAPODS OF THE CAPE. 
69 
Tribe. TRIGONOSTOMA. 
Aberrant Groupe. 
Macrocera. 
External antenna: long, or at 
least conspicuous. 
I 1 CoRYSTINA. 
2 Dorifpina. 
U! Dromiina. 
Normal Groupe. 
4 Leucosina. 
Brachycera. 
External antenna more or* 
less rudimentary and al- 
ways inconspicuous. 
5 Calappina. 
C External antennae long. Hind feet of the more usual struc- 
j ture, and serving for locomotion. Oral orifice triangular. 
f External antennae long. Hind feet raised up over the 
{ hack and serving for organs of prehension. Oral orifice 
l_ triangular. 
I 
L 
External antennse moderate. Hind feet raised up over 
the back and serving for organs of prehension. Oral 
orifice not always triangular. 
f Anterior feet not elevated into a crest. No branchial 
afferent apertures in front of the fore feet. 
f Anterior feet compressed and elevated into a crest. Bran ■ 
cbial afferent apertures in front of fore feet. 
15. From the Corystina we pass to the Calappina, by means of Matuta. By Oreophorus we 
leave the Calappina for the Leucosina. The passage from the Leucosina to the Dromiina is 
not so clear; but these last 'are close to the Dorippina, which last again are approximated 
naturally to the Corystina. Still the tribe has never been worked out, and I think it more 
than possible that the Dromiina which I have here considered to be an aberrant groupe of 
Trigonostomous Brachyura, will, in the end, be found to be an aberrant groupe of Anomurous 
Macroura. Nay, this last is the position assigned to it by Milne Edwards, and the arguments 
for such a location of Dromiina are their rudimentary abdominal appendages, and the oral orifice 
being rarely triangular. On the other hand, however, they differ from all Macroura in having 
fossulffi for the reception of their internal antennae. The question therefore of their true place can 
only be determined when the groupe shall have been worked out, which I fear cannot be done at 
present, on account of the paucity of species which are known to belong to this essentially tropical 
tribe. One thing, nevertheless, is established, namely, that the Dromiina are osculant, or, in other 
words, they stand on the limits of the Trigonostomous Brachyura and Anomurous Macroura. 
Into which of these circles the stirps truly enters, must be left for future investigation ; but 
I shall provisionally consider it as belonging to the Brachyura. As for the families of 
Trigonostomous Brachyura, I shall not at present attempt to indicate them, but proceed at 
once to characterize the sub-genera brought from the Cape, which are only three. 
Stirps. CORYSTINA. 
Of the stirps Corystina we have no species from the Cape; but the following is very close 
to it, being aberrant in the next stirps. 
