OF THE COASTS OF SOUTH AMERICA. 43 
with numerous strong spines and tubercles, one longer than the rest standing out hori- 
zontally on each branchial region. Latero-anterior margin with three spines, and a 
fourth behind them which forms the commencement of a flattened ridge extending 
backwards to the posterior margin. Orbits with a strong spine over the inner canthus. 
Rostrum very prominent, flattened, terminating in two strong diverging teeth. 
Exterior antenne cylindrical, inserted at the side of the rostrum, and not at all con- 
cealed by it. The pedipalps similar to those of the other species of the genus. 
The abdomen of the male formed of seven distinct joints, each elevated in the centre, 
so as to form a longitudinal carina. The divisions of the sternum very distinct. 
The anterior pair of legs twice the length of the body; the arms furnished with nu- 
merous obtuse spines: the hands granulated, and without spines: the fingers touch 
each other only at the points, which are rather acute. The four posterior pairs of legs 
diminish regularly from the second to the fifth ; they are wholly without spines, con- 
siderably thickened at the joints, and terminate in a strong curved nail. 
The colour of the hair which covers the whole animal is a light brown; the body 
itself paler. 
Length of the carapax, including the rostrum, 2 inches 8 lines ; breadth 2 inches 3 lines. 
A single male specimen only was found by Mr. Cuming on the Peruvian coast, in 
soft mud, at the depth of five fathoms. 
This species differs from all others previously known in the genus, in a character 
which, unless a new genus were formed for its reception, requires the revision and al- 
teration of the generic character as hitherto assigned to it. The rostrum, instead of 
being extremely small, and merely notched at the extremity, is broad, projecting, and 
terminates in two strong, diverging teeth. The other characters of the species, and its 
general habit and form, are, however, so essentially those of the genus Tibinia, that I 
cannot but consider it as belonging to the same natural group. 
Genus Ruoptia. 
Testa pyriformis, in rostrum parvum, bidentatum anticé producta. 
Oculi retractiles, globosi, pedunculo crassiores. 
Orbita fissura magna, superné aperta. 
Antenne interiores in foveolis profundis, lunatis, anticé separatis receptz. 
Antenne exteriores rostro duplo longiores, articulo basilari bidentato, reliquis cylindricis, 
ad rostri latera insertz. 
Pedum par anticum aris (immaturi) reliquis brevius ; digitis minutissimé serratis : 
paria quatuor posteriora testa longiora, 4 secundo ad quintum sensim paulld breviora. 
Abdomen Manis 7-articulatum. Famin«? 
This genus is allied to Herbstia, from which, however, it differs remarkably in the 
structure of the anterior feet. The fingers in Rhodia meet throughout their whole 
length and the margins are minutely serrated : in Herbstia they meet only at their 
G2 
