MUSEUM OF COMPARATIVE ZOOLOGY. 101 
curved or hooked at the tip. The mandibles (Pl. IV. Fig. 3a) are robust at 
base, but slender and acute at the tip. 
In the prehensile, or first three pairs of legs, the merus, carpus, and pro- 
podus are each armed with a short, curved, blunt spine on the palmar margin, 
as shown in the figure of a leg of the first pair on Plate IV. Fig. 3d. The 
remaining four pairs of legs, not all natatory, are well fitted for prehension by 
their slender curved claws, and differ considerably in their proportions in speci- 
mens of different sizes, as shown by the accompanying table of measurements. 
All the legs are strongly flexed at the articulation of the basis with the ischium. 
In the sixth and seventh pairs, the ischium, merus, carpus, and propodus are 
elongated and in the small specimens slender, so that, with the addition of the 
dactylus, the last five segments of the leg of the sixth pair may attain to five 
sixths or even seven eighths the length of the body. The bases do not partici- 
pate in this elongation and are therefore omitted in the measurements, since to 
include them would only diminish the contrast between the large and small 
specimens, shown especially in the last six columns of the table. In large 
specimens, like the one figured, the sixth and seventh pairs of legs are much 
more robust than in smaller ones. 
The pleopods (Pl. IV. Fig. 3g) are not naked, as originally described, but 
all the anterior ones, as usual in the gid, are distinctly ciliated. The cilia 
are however short and not very evident, and were overlooked in the single 
specimen described. In the small specimens they are proportionally longer 
than in larger ones. The second pair of pleopods in the male (Pl. IV. Fig. 
3 g) bears a slender stylet tapering to the tip, and about as long as the ramus to 
which it is attached. In the small specimen, whose measurements are given 
in the last column of the table, the stylet is blunt, and considerably shorter 
than the ramus. The uropods (Pl. IV. Fig. 3h) are robust; the basal segment 
is oblique, but not much produced internally; the rami are well ciliated. 
Professor Verrill states that in life this species is bright colored, varying 
from bright orange to salmon-colored above and light yellow underneath. This 
color soon fades in alcohol. 
Considerable variations in size, and corresponding variations in the propor- 
tions, especially of the sixth and seventh pairs of legs, are shown in the fol- 
lowing table of measurements, in which the first three columns contain 
measurements of the Blake Expedition specimens, the next four columns con- 
tain measurements of specimens obtained at a single locality (Station 945) off 
Martha’s Vineyard, by the U. S. Fish Commission in the summer of 1881, 
while in the last column are measurements of a smaller specimen obtained by 
the Fish Commission at another locality (Station 1028) in the same region. 
The measurements in the fourth column are from the specimen figured on 
Plate III. Figs. 5 and 5a; those of the next five columns are from specimens 
gradually decreasing in size to the last. The length of the ambulatory legs, 
especially those of the sixth and seventh pairs, is seen to increase proportionally 
as the length of the body diminishes, except in the case of the seventh pair 
of legs of the last specimen. This is doubtless to be explained as a mark of 
