MICHIGAN ACADEMY OF SCIENCE. 
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proximal margin in median line. Uropoda with basal segment a little 
longer than wide; inner branch robust, spatulate, more than half as 
long as pleotelson, attached on the posterior inner margin of basal seg- 
ment; outer branch small, conical, inserted more on the dorsal than 
ventral surface of the basal segment at the middle of its inner margin. 
Color of alcoholic specimens slaty; a series of longitudinal median white 
blotches along the segments from the head to the pleotelson; lateral 
margins of first, third, fourth and all abdominal segments more or less 
white. Dimensions: 11 by 5.5 millimeters. 
Eleven 'specimens of this species (41700, 41709, 41711, 41712, 41713) 
were collected between August 3 and August 13, 1910. The two type 
specimens were taken at Cuatotolapam, August 4, and all of the others 
were secured at the same place. All of the individuals were found under 
logs, leaves or stones. The species is named for Bryant Walker of De- 
troit, Michigan, whose generosity made the expedition possible. 
4. Probopyrns bithynis Richardson.— A specimen of this species was 
found by Miss Rathbun within the branchial chamber of one of the speci- 
mens of Maerobrachium olfersii. According to Miss Rathbun this is 
the first time that the species has been found parasitic on this shrimp. 
5. Porcellio rathkei Brandt (?), — Several specimens thus identified 
by Dr. Richardson were taken in decaying palm trees in low jungle at 
Cuatotolapam. Dr. Richardson states that the markings differ from 
those shown by individuals from the United States, but that this is 
probably but a variation exhibited by P. rathkei. 
AMPHIPODA. 
6. Hyalclla ornata, new species. — -Body slightly compressed; pleon 
segments 1 and 2 each produced into a dorsal spine in large individuals. 
Head longer than first peraeon segment; eyes large, elongated, elliptical. 
Side plates 1-4 rectangular with rounded corners. Pleon segments 3, 
posterior lateral angles slightly produced, tip rounded. Antenna 1 
reaching beyond middle of flagellum of antenna 2, flagellum longer than 
peduncle, 6-7 segmented. Antenna 2 with ultimate segment of peduncle 
a little longer than the penultimate, flagellum longer than peduncle. 
Maxilla 1 with four plumose setae on apex of inner plate, Gnathopods 
ornamented with low, cresentric, hairy tubercles. Gnathopod 1 slender, 
palm transverse, sinous, defined by a tubercle. Gnathopod 2 in male, 
sixth joint stout, longer than broad, palm oblique, a notch near the base 
of the finger and a tubercle at the defining angle; finger stout, curved. 
Gnathopod 2 in female weak and slender, fifth and sixth joints both 
swollen into a large tubercle on the posterior margin, sixth about twice 
as long as broad, posterior margin longer than front; palm nearly 
straight, a shallow notch at base of finger. Posterior margin of second 
joints of peraepods 2-4 smooth, posterior margin of 5 serrate. Peraepod 
4 not quite as long as 5. Ramus of uropod 3 as long as peduncle, slender, 
tapering, with a tooth and two setae at apex. Telson about as wide as 
long; apical margin thin and rounded, a slender setae on each side of 
apex. Length, 4 mm. 
This species is given the name ornata on account of the tubercles which 
cover parts of the anterior margins of the last two segments and the 
