GENERA UEOTHOE AND UEOTHOIDES. 19 



joint rather longer, scarcely broader, with a group of setae and a spine at the indent of 

 the front margin, the apex of which has five spines : a row of seven spines arms the 

 lower margin of the outer surface and the rounded hinder apex, the corresponding 

 margin of the inner surface being fringed with some sixteen immensely long and 

 densely plumose setae, some of which reach to the extremity of the limb ; there are 

 sometimes short plumose setae along the hind margin ; the fourth joint is nearly as 

 long as the two preceding joints together, and decidedly, yet not very greatly, wider than 

 either; on the outer surface there is a series of eight unequal spines reaching the 

 indent of the front margin, and another reaching that of the hind margin ; below these 

 there are two distal series, respectively of six and eight spines, and on the hinder part 

 of the distal margin there are also on the inner surface some long plumose setae ; the 

 fifth joint is longer, but very much narrower than the fourth, having at the middle of 

 the hind margin a group of five unequal spines, and of three at the apex, on the 

 strongly indented front margin three groups of seven, six, and five respectively, and 

 on the inner surface below the middle a row of five long densely plumose setae ; the 

 finger is not much shorter than the fifth joint, comparatively broad, except near the 

 cap-bearing tip, containing, like almost all other parts of the animal, numerous gland- 

 cells with their ducts and minute circular openings ; the hind margin almost straight, 

 carrying near the base a small plumose cilium, the front margin at first smooth, but for 

 two thirds of its length armed with nodules, about thirteen in number, the first eight 

 or nine successively larger, the next one, two, or three small and sharper than the rest, 

 followed by one near the tip longer than any of the others. 



Fourth per ceojiods. Side plates narrower than in the preceding pair, the hind margin 

 crenate and fringed with spinules. The branchial vesicle smaller than in the preceding 

 pair. The first joint large and oval, rather broader below than above, the front margin 

 a little sinuous, with two or three spinules above, and three or four gi'oups of pectinate 

 setiform spines below ; the convex hind margin veiy shallowly crenulate, with spinules 

 in the indents ; the wing has numerous gland-cells, and sometimes as many as sixteen 

 long and very plumose setae, planted in a slight curve a great way from the margin on 

 the inner surface ; the short second joint has a group of pectinate spines at the apex of 

 the front margin; the third joint, which is more than twice as long as broad, has three 

 groups of spines along the front, nine long, much flattened, setae along the hind margin, 

 and a spine at its apex ; the fourth joint is longer than the third, and has four groups 

 of rather stout spines along the front, and three mixed groups along the hind margin ; 

 the fifth joint is narrower than the fourth, scarcely longer than the third, with three 

 groups of stout spines along the front, one a't the sharply produced apex of the hind 

 margin, and a little higher up a slender group ; the finger is half the length of the 

 fifth joint, straight, very slender, with a plumose cilium on the hind margin near the 

 base, several little nodules along the front, of these that near the curved tip of the 

 finger being as usual the largest. 



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