REPORT ON THE BRACHYURA. 
153 
The dimensions of the largest male are as follows : — 
Adult 3 . 
Lines. 
Millims. 
Length of carapace, nearly . 
H 
7-5 
Breadth of carapace, about . 
41 
9-5 
Length of a chelipede, nearly . 
6 
12-5 
Length of second ambulatory leg, 
6f 
13-5 
A small male Pilumnus is in the collection from St. Thomas (shallow water), which 
I cannot certainly refer to any species of this very difficult genus, yet do not venture to 
constitute the type of a distinct species. It is allied to Pilumnus quoyi, Milne Edwards, 
as described and figured by A. Milne Edwards, in many characters, and particularly in 
the rounded tubercles of the exterior surface of the palms of the chelipedes, which, 
however, become spinuliform on the superior margins ; it differs from that form in 
having a few very small spinules interspersed among the hairs of the ambulatory legs, 
&c. Pilumnus miersii, A. Milne Edwards, to which it is also nearly allied, has an 
additional antero-lateral spine. Pilumnus lacteus, Stimpson, which it resembles in the 
whitish pubescence of the body (interspersed with longer hairs), is distinguished by the 
smooth exterior surface of the palms of the chelipedes. 
Adult 3 . 
Length of carapace, about 
Breadth of carapace, about 
Pilumnus fragosus, A. Milne Edwards, var. 
Pilumnus fragosus, A. Milne Edwards, Crust, in Miss. Sci. au Mexique, pt. 5, p. 296, pi. lii. 
fig. 1, 1880. 
Bahia (7 to 20 fathoms). Two females. 
In these specimens the tubercles of the carapace and of the chelipedes are less flattened 
and less distinctly pedunculated than in the figure of Milne Edwards, whose types w T ere 
from the island of St. Thomas. There exists a second row of less elevated tubercles 
behind the tubercles of the protogastric and epigastric lobes which are not shown in the 
figure cited. I think it therefore possible that the Challenger specimens may prove to 
be specifically distinct. 
The largest example measures as follows : — 
Adult 5 . Lines. Millims. 
Length of carapace, . . . . . . . 3J 7 '5 
Breadth of carapace, about . . . . . . 4-|- 9’5 
This specimen bears ova, and is, therefore, fully adult ; some longer hairs are inter- 
spersed among the short greyish-brown pubescence of the carapace and limbs ; these hairs 
are slightly clavate. 
(ZOOL. CHALL. EXP. — PART XLIX. 1886.) 
Lines. Millims. 
2 4-5 
n 5-5 
Ccc 20 
