PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. a0 
The branchiz are the same in number and arranged in the same way 
as in Hupagurus bernhardus, as indicated in the following formula : 
Somite— 
Ve | Velie Bi xt | xu. | xu. | x1v. | Total. 
1) 00 
Podobranchiz............- 
Arthrobranchiz.........-- 
Pleuxobranchie....-.....- 
} 0 
0 
ococco 
Ses 
onoo : 
conoo 
onoco 
lh) 
S22 
0 
0 
| 
| 11 
But, as stated in the original description, they are trichobranchiz, not 
phyllobranchiz as in ordinary Paguroids. In the original specimen, 
and in all those not preserved with special care, the branchie are flaccid 
and the papillz of which they are composed are collapsed, apparently 
cylindrical throughout, and without definite arrangement along the stem 
of the branchia; but in specimens carefully preserved in strong alcohol 
the papille in the thicker parts of the branchie are seen to be slightly 
flattened toward their bases in the direction of the axes of the branchiz, 
and to have a definite arrangement in four longitudinal series, showing, 
in a transverse section of the branchia, two papille either side of the 
central axis in place of the thin lamella attached by one edge to either 
side of the lamelliform central stem of the phyllobranchia of ordinary 
Paguroids. Toward the tips of the branchize the papille become truly 
cylindrical as in Homarus or A stacus, and in some of the smaller branchiz, 
as in the arthrobranchiz of the external maxillipeds, the papille upon 
one side of the branchia are very small or rudimentary; but in all cases 
the ultimate divisions of the branchie are apparently strictly tricho- 
branchial in structure, the blood vessels on either side of each papilla 
giving off capillary branches in opposite directions to the surface of the 
papilla. The structure is essentially as in Astacus, and the difference 
is not apparent without close examination. From ordinary Paguroids, 
like Eupagurus bernhardus, however, it is widely different, but this dif- 
ference is partially bridged by the structure of the branchie in Sympa- 
gurus pictus about to be described, although there the branchiz are es- 
sentially phyllobranchiz. 
In the chelipeds the merus, carpus, and chela are very densely clothed, 
except at the tips of the digits, a space on the under side and at the base 
of the chela, and the inner side of the merus, with a very fine and soft 
pubescence usually loaded with fine mud when the specimens are first 
taken. 
Individuals differ considerably in the form and proportions of the cheli- 
peds. In one large male, measurements of which are given in the last 
column in the accompanying table of measurements, the right cheliped 
is only very slightly longer and scarcely stouter than the left, and the 
chela differs from that of the left only slightly in form. The defective 
development of the right cheliped in this specimen probably resulted 
