944 PROCEEDINGS OF THE NATIONAL MUSEUM. VoL. XXXIV. 
vesicles are narrowly twisted. The marsupial plates of the female 
examined do not seem to be fully developed. 
The slender pleopods have along the peduncles two rows of short 
spines and two coupling-hooks. The rami are about nine-jointed, and 
are scarcely as long as the peduncles. 
The first uropods have the peduncle longer than the subequal rami, 
one of which has conspicuous spines only at the apex. The second 
pair have one ramus much longer than the other, with the peduncle 
Fic. 2.—ORCHESTOIDEA BIOLLEYI, FEMALE. 
of intermediate length. The third pair have the ramus about equal 
in length to the peduncle. The telson is about as broad as long, 
distally tapering, with a dividing line running up some part of the 
length from the apex. 
Length of male about 10 mm., of female about 7.5 mm. 
[Tabitat.—Several specimens were collected in February, 1907, at 
Punta Arenas, Costa Rica (Pacific coast), in sand, under trunks of 
trees, by the late Professor P. Biolley, out of respect to whom the 
specific name has been given to this species. 
L'ype.—Cat. No. 38348, U.S.N.M. 
HXPLANATION OF PLATE XII. 
nm s&s f$, Wu. Ss. 9. Lines indicating natural size of male and female specimens, 
from which the details have been figured. 
a. 8., d. 1. Upper and lower antennee of male. 
“mx. 1. First maxilla of male, the inner plate seen by transparence through 
the outer. The scale of magnification higher than in the other figures. 
gn. 1, gn. 2, gn. 1. 9, gn. 2, 9. First and second gnathopods of the male and 
female, with portions of the same more highly magnified. 
prp. 1, 2, 3, 4, 5. The five pereopods, with parts of the first, second, and fifth 
more highly magnified. 
urp. 1, 2, 3, 7. The three uropods and the telson, with the latter more highly 
magnified. 
Two uniform scales have been used for the lower and higher enlargement 
of all the parts except the first maxilla. A 
