OF THE COASTS OF SOUTH AMERICA. 63 
footstalk having parallel sides, except at the apex, which is triangular ; inner footstalk 
smooth and polished, with the second joint truncated at the inner and posterior angle. 
Abdomen of both sexes with seven joints. 
Anterior feet of the male very robust, nearly twice as long as the carapax, very mi- 
nutely granulated: the arm with two tubercles above and two beneath: the hand 
rounded, smooth ; the fingers strongly tuberculated through their whole length, meeting 
only at the points, which are somewhat excavated ; the moveable finger longer than 
the other. Posterior feet cylindrical, the joints tumid: the second pair longer than the 
hinder ones, which decrease in length to the fifth. A tooth on the inferior side of the 
penultimate joint, which is hairy at the point: it is smallest on the second pair and 
longest on the fifth. The last joint is curved, acute, and finely toothed beneath. 
Colour of the adult dark brown ; of the young female, paler and reddish. 
Length of the carapax 4 inches ; breadth 3 inches 3 lines. 
The large male specimen was found by Mr. Cuming with Ep. dentatus at Valparaiso 
in crevices of rocks. The young female specimen was brought by Mr. Miller from Rio 
Janeiro. 
It is not without considerable hesitation that I have decided on giving to these Crus- 
tacea the characters of distinct species. I was first led to the opinion that they were so, 
by comparing with Mr. Cuming’s specimens of Epialtus one of an immature female 
which was kindly presented to me by Mr. Miller, and which he had taken at Rio: and 
a subsequent more particular examination of the former specimens has tended greatly 
to confirm this view, as the largest and finest of them, a very fine adult male, possesses 
all the characters which had led me to consider Mr. Miller’s specimen as distinct. 
I have thought it desirable to offer a figure of each of these two individuals, and as they 
differ from Ep. dentatus only in slight characters, which are easily appreciated, it ap- 
peared unnecessary to figure that species, especially as it has been described by my 
friend Dr. Milne Edwards, and will I hope shortly be figured by him. : 
The characters upon which I have founded this distinction are these. In Ep. dentatus 
the lateral margin is rounded, the sides of the carapax passing off from above to beneath 
in a continuous rounded surface: in Ep. marginatus the upper and under surfaces are 
separated by a distinct slightly salient margin ; the posterior tubercle, whick in the 
former is very distinct, is in the latter only indicated by a very slight degree of promi- 
nence in the marginal line ; and the lateral spine of the former is in the latter supplied 
by a tubercle. The very great difference in the size of the anterior feet probably de- 
pends on age: but it is worthy of notice that in the rest of the feet the inferior spine 
near the extremity of the penultimate joint, is much smaller and shorter relatively in 
Ep. dentatus than in Ep. marginatus. 
